- Email: [email protected]
Electrical properties of be-implanted GaA1-xPx
.W&%le
EIacfmn&~, 1976,Vol. 19. pp. %I-%&
ELECTRICAL PROPERTIES OF Be-IMPLANTED GaAsl_, P, t PALLABK. CHATTERJEE, W. V. MCLEVIGEand B. G.
STREETMAN
Coordinated Science Laboratory and Department of Electrical Engineering, University of Illinois at UrbanaChampaign,Urbana, IL 61801,U.S.A. (Receiued 29 March 1976;in revisedfonn 26 April 1976) Abstract-Hall effect and resistivity measurements on Be implantedGaAs,_,P.(x - 0.38) indicate that essentially 100%doping efficiencymay be obtainedfor normalBe concentrationsaftera !NOTannealus& eitherSiO, or S&N, as an encapsulant. The temperaturedependence of hole mobility in these samples exhibits impurity banding effects similar to those reported in heavily Zn doped &As. Hall effect measurements in conjunction with successive thin laver removal teclmiaues indicate there is no sianificant diffusion of the implanted Be during anneal for a fluence of 6 x 10” ions/cm*. _ INTROJXICI’ION
Vapor phase epitaxially grown GaAs,_, P, wafers of the standard composition (x - 0.38) for manufacture of red light emitting diodes were used in this study. The crystals were grown by Monsanto Co. and had a donor concentration ND = 4 x lOI cm-‘. The Be implantations were performed at room temperature at 250 keV to various fluences, using a cold cathode source in the sputter ion mode as described elsewhere[21. Following
implantation, the samples were encapsulated with - 1500A of SIN, (obtained by RF plasma deposition at SOOOC) or SiOZ(obtained from the oxidation of silane at 45O’C). The encapsulated samples were annealed in flowing argon at various temperatures between 600 and 900°C. The encapsulating layer was then removed by etching and a van der Pauw[8] contact pattern was defined by the evaporation of AgMn[9] through a shadow mask. To minimize the effects of contact size[lO], grooves were sandblasted on the sample surface through another shadow mask to define a cloverleaf-type geometry. The Hall effect and resistivity measurements were performed using the double ac method[ll, 121, which employs a separate frequency for the exciting current and the magnetic field. The Hall voltage appears at the heterodyne frequencies and can be measured by lock-in techniques. This frequency domain separation of Hall voltage from the zero field voltage allows very small Hall voltages (-10 nV) to be measured. The ac excitation eliminates the various averaging methods normally used to cancel thermoelectric, thermomagnetic, and misalignment errors. The temperature dependences of the Hall effect and resistivity were measured using a coldfingertype liquid nitrogen cryostat wlth a built-in magnet [ 131.A calibrated platinum resistance thermometer was used simultaneously with a chromel-ahunel thermocouple with a digital readout to monitor the sample temperature. The temperature of the coldflnger was varied using resistive heating, and the sample temperature was held constant to *lo while the measurements were taken. The layer removal technique used in this study consisted of repetitively growing a thin anodic oxide layer using a KMnO,-acetone solution[lC 151and then chemically etching the layer in HCl. Tsang[lS] has calibrated the oxide layer thickness to the charge passed through the cell, and we have used this method of depth calibration in this study.
tWork supported by the Joint Services Electronics Program (U.S. Army, U.S. Navy, and U.S. Air Force) under Contract DAABM-72-C-0259,and by MonsantoCompany.
of
Beryllium ion implantation in GaAs has been demonstrated to produce p-type IayQs with good ekctrical
activation[ l] and efficient hnninescence[2] after proper annealing, although controlled Be doping is di5cult by standard diffusion[3] or growth[4] techniques. It has recently been reported that Be ion implantation may be used to fabricate red light-emitting diodes in GaAs,_,P.(x - 0.38)[5] and that proper annealing can result in restructuring of the lattice and excellent optical activation[6]. In this paper we present Hall effect and resistivity measurements on Be implanted GaAs,_, P. (x 0.38) layers. It is shown that annealing at 900°Cwith Si,N, or SiO, encapsulation results in excellent electrical activation of the implanted Be, with a doping efficiency of -100% for Be fluences ~10” ions/cm-’ at 250 keV. The maximum Be concentration for such an implant on the basis of LSS theory[7] is ~2.5 x 1018cm-‘. Temperature dependence of the Hall effect data obtained from Be implanted layers exhibits impurity conduction effects for Be fluences ~6 x 10” ions/cm* at 250 keV. Hall effect measurements performed in conjunction with layer removal by anodic oxidation and chemical stripping of the oxidized layer yields a distribution of the electrically active Be which is very close to that predicted by the LSS theory[7]. This suggests that there is no significant d.iEusion of the implanted Be during the anneal, for a fluence of 6 x 10’”ions/cm’.
961
Figure 1 illustrates the anneal temperature dependence sheet carrier concentration and mobility for
et al. P. K. CHATTEFSEE
962
GaAso.62 P0.g
implanted GaAs,_, P, (x - 0.38), which are consistently lower than those reported here for Be implanted material. However, the quality of the substrate material is extremely important in comparing mobility data, and these differences may reflect better crystal structure of the wafers used in this study, rather than inherent differences between Zn and Be doping. The data presented in Fig. 1 were obtained from samples annealed with S&N, encapsulation. Hall effect measurements on samples annealed with SiO, encapsulation resulted in sheet carrier concentrations and mobilities that were remarkably close (21%) to those obtained with S&N,. This leads us to conclude that the encapsulating dielectric for annealing GaAs,_, P, (x - 0.38) does not determine the activation and lattice restructuring properties as critically as is the case for GaAs[2]. The reason for this difference between GaAs and GaAs,_, P, is unclear. The presence of phosphorus perhaps reduces the tendency of the crystal to form native defects during heat treatment. It may also be argued that since a large density of deep level defects are already present in the GaAs,_, P, crystal[l8], differences in defect generation during anneals with the two encapsulants may be insignificant by comparison.
Be Implant
250 keV 0 6x1014cni2
a 1.1x1014 0 6X1013
TEMPERATURE DEPENDENCE
<
1
1
I
700 800 Anneal Temperature (“C)
9’
Fig. 1. Hall mobility and sheet carrier concentration as a function of isochronal anneal temperature for G~As~.~~P~.~~samples implanted with 250 keV Be to the doses shown.S&N,encapsula-
The temperature variation of Hall mobility in Be implanted GaAs,_,P,(x - 0.38) samples is shown in Fig. 2. The relatively heavy implantation doses used were necessary because of the practical problems associated with making ohmic contacts to lightly doped p -GaAs,_, P,. The temperature dependence of mobility for the doping densities used is similar to that reported in Zn doped GaAs [ 191.The mobility is dominated by lattice scattering 0
r
GaAs0.62 Pose Be Implant 250 keV. 900°C Anneo I
0 fi 0
tion wasusedfor the anneals. GaAs,_,P,(x - 0.38). Samples were Be implanted to various doses and annealed for 1 hr at temperatures between 600 and 900°Cwith Si,N4encapsuiation. The sheet carrier concentration increases with anneal temperature, whereas the mobility is roughly independent of anneal temperature. The maximum value of sheet carrier concentration agrees remarkably well with implantation fluences up to 1.1x 1014ions/cm*. At higher fluences the sheet carrier concentration is lower than the fluence, becoming about 60% of the fluence for a dose of 6 x lOI ions/cm2. Since the maximum impurity concentration for this implantation on the basis of the LSS theory [7] is about 1.5 x lOI cmm3,partial activation is not very surprising. The doping efficiency reported here is significantly higher than that obtained for donor implants in GaAs [ 161. The hole mobility in GaAs,_, P, (x - 0.38) is lower than that in GaAs, presumably due in part to alloy (As, P) disorder in the ternary system. Very little data has been reported for mobilities in p-type GaAs,_,P,. Stoneham [ 171has recently measured Hall mobilities in Zn
160
_ 240 lemperature
,_..,
6x10’+cr%z l.lX10’4 6~10’~
320
L 3
i-K1
Fig. 2. Hall mobility as a function of temperature for GaAs, 62P0.38 samples implanted with 250 keV Be to the doses shown, and annealed at9OOT for 0.5 hr.
963
Electrical properties of Be-implanted GaAs,_,P,
at temperatures above 12O”C,and impurity scattering dominates at lower temperature. The Hall coefficient and resistivity data obtained from these samples show features of impurity banding, as expected for the doping density used. The Hall coefficient reaches a maximum value and then decreases with decreasing temperature. The presence of impurity banding makes it difficult to estimate the binding energy of Be in GaAs,_,P,(x - 0.38). However, the similarity of this data to that reported for Zn doped GaAs indicates that implanted Be serves as a shallow acceptor similar to Zn in this material. Recent photoluminescence measurements on more lightly doped material indicate an acceptor binding energy of 35? 3 meV for Be in GaAs,_,P,(x 0.38)[6]. DEPTHDISTRIBuTlON
Figure 3 presents the distribution of implanted Be obtained from Hall effect measurements in conjunction
with successive anodic oxidation and stripping. The sample was implanted to a fluence of 6 x lOI ions/cm* and annealed at 900°C for 0.5 hr with S&N.,encapsulation. We have also included the depth distribution expected on the basis of LSS theory[7]. For this doping level the measured profile agrees very well with the predicted gaussian distribution. It is clear that very little diffusion of the implanted Be takes place during anneal for a relatively high doping concentration (-10’” cm-“). This result is very significant in the context of device fabrication. It is likely that higher fluences (a1O’4cm-‘) may lead to anomalous Be diffusion as has been observed in heavily doped GaAs[20]. In contrast with results reported here, implanted Zn diffuses rapidly during anneal in this material, even for moderate doping levels. As a result, the electro-optical properties obtained are characteristic of Zn
diffused into the undamaged bulk, and do not indicate the quality of the implanted layer. The electrical activation data presented here are obtained from the implanted layer, since Be does not diffuse significantly, and provide strong evidence of the high crystal quality of these layers. SUMMARY
We have presented Hall effect and resistivity data for Be implanted GaAs,_,P,(x - 0.38). Annealing at 900°C with SiO, or S&N4 encapsulation produces excellent electrical activation of the implanted Be, with a doping efficiency of essentially loo%, for Be doses up to - 10” ions/cm’ at 250 keV. The temperature dependence of mobility shows impurity banding effects typical of heavy acceptor doping. Hall effect measurements in conjunction with thin layer removal by anodic oxidation and stripping indicate that the distribution of implanted Be after anneal is very similar to that predicted by LSS theory, for a fluence of 6 x lOI ions/cm*. Thus, there is no significant diffusion of Be during anneal at this fluence. Multiple energy implants may, therefore, be used to synthesize acceptor profiles suitable for special device applications. For example, it is possible to investigate the effect of various acceptor profiles on the performance of light emitting diodes fabricated in this material[5,21]. Furthermore, observations by scanning electron microscopy [21] indicate negligible lateral diffusion of implanted Be under Si3N4 masks, in contrast with extensive lateral motion of diffused Zn. Be is thus a useful acceptor in GaAs,_,P, for fabrication of devices requiring good electrical activation, special acceptor distributions, and precise lateral dimension control.
Acknowledgements-We
/
1
I
I
I
would like to thank D. L. Keune of Monsanto Co. for providing the crystals for this work.
I
Go%., POza
“Er”
Be 25qlp 6E13 cm 900°C Anneal
m
REFERENCES
1. R. G. Hunsperger, R. G. Wilson and D. M. Jamba, .I. Appl. Phys. 43, 1318(1972). 2. P. K. Chatterjee, K. V. Vaidyanathan, W. V. McLevige and B. G. Streetman, Appl. Phys. Lett. 21, 565 (1975). 3. E. A. Poltoratskii and V. M. Stuchebnikov, Sou. Phys. So/id &ate 8, 770 (1%6).
4. D. J. Ashen, P. J. Dean, D. T. J. Hurle, J. B. Mullin, A. M. White and P. D. Greene, J. Phvs. Chem. So/ids 36. 1041 (1975). 5. P. K. Chatterjee, B. G. Streetman, D. L. Keune and A. H. Herzog, IEEE IEDM Tech. Digest 187(975). 6. P. K. Chatterjee, W. V. McLevige and B. G. Streetman, L Appl. Phys. (1976). To be published. 7. J. Lindhard, M. SchartTand H. Schi#tt, Mat. Fys. Medd. Vid. Schlsk 33, 1 (1963). 8. L. J. van der Pauw, Phillips. Res. Rep. 13, 1 (1958). 9. T. Itoh and Y. Oana, J. Appl. Phys. 44, 4982 (1973). 10. R. Chwang, B. J. Smith and C. R. Crowell, Solid- St. Electron
7 t
17, 121 (1974).
6L 0 Depth
(pm)
1.4 LPll93
Fig. 3. Distribution of implanted Be obtained from differential Hall effect measurements for a GaAh,,P,, sample implanted with 250keV Be to a dose of 6 x 10’”ions/cm2.The Be distribution predicted on the basis of LSS theory[7]is superimposed.
11. B. R. Russell and C. Wahlig,Rev. Sci. Instr. 21,1028(1950). 12. T. Kaneda, S. Kobayashi and K. Shimoda, Jap. J. Appl. Phys. 12, 1335(1973). 13. M. Altwein, H. Finkenrath and T. Stockel, J. Phys. E. 6,623 (1973). 14. E. B. Stoneham, I. Elec&ochem. Sot. 121, 1382(1974). 15. D. Z. Tsang, M. S. Thesis, University of Illinois, 1975.Also,
964
P. K. CHATTERJEE et al.
Coordinated Science Laboratory Report R-708, UILU-ENG, 75-2244(1975).Available from NTIS, Springfield, Virginia. 16. J. F. Gibbons and R. F. Tremain, Jr., Appl. Phys. Lett. 26, 199 (1975). 17. E. B. Stoneham, Tech. Report 4733-l. Stanford Electronics Lab., California (1975). 18. L. Forbes, Solid-St. Electron. 18, 635 (1975).
19. F. Ermanis and K. Wolfstim, I. A@. Phys. 37,1%3 (1966). 20. J. Comas, Naval Research Laboratory, private communication. 21. P. K. Chatterjee, Ph.D. Thesis, University of Illinois (1976); also, Coordinated Science Laboratory Report R-721, UILUENG, 76-2209(1976).
EIacfmn&~, 1976,Vol. 19. pp. %I-%&
ELECTRICAL PROPERTIES OF Be-IMPLANTED GaAsl_, P, t PALLABK. CHATTERJEE, W. V. MCLEVIGEand B. G.
STREETMAN
Coordinated Science Laboratory and Department of Electrical Engineering, University of Illinois at UrbanaChampaign,Urbana, IL 61801,U.S.A. (Receiued 29 March 1976;in revisedfonn 26 April 1976) Abstract-Hall effect and resistivity measurements on Be implantedGaAs,_,P.(x - 0.38) indicate that essentially 100%doping efficiencymay be obtainedfor normalBe concentrationsaftera !NOTannealus& eitherSiO, or S&N, as an encapsulant. The temperaturedependence of hole mobility in these samples exhibits impurity banding effects similar to those reported in heavily Zn doped &As. Hall effect measurements in conjunction with successive thin laver removal teclmiaues indicate there is no sianificant diffusion of the implanted Be during anneal for a fluence of 6 x 10” ions/cm*. _ INTROJXICI’ION
Vapor phase epitaxially grown GaAs,_, P, wafers of the standard composition (x - 0.38) for manufacture of red light emitting diodes were used in this study. The crystals were grown by Monsanto Co. and had a donor concentration ND = 4 x lOI cm-‘. The Be implantations were performed at room temperature at 250 keV to various fluences, using a cold cathode source in the sputter ion mode as described elsewhere[21. Following
implantation, the samples were encapsulated with - 1500A of SIN, (obtained by RF plasma deposition at SOOOC) or SiOZ(obtained from the oxidation of silane at 45O’C). The encapsulated samples were annealed in flowing argon at various temperatures between 600 and 900°C. The encapsulating layer was then removed by etching and a van der Pauw[8] contact pattern was defined by the evaporation of AgMn[9] through a shadow mask. To minimize the effects of contact size[lO], grooves were sandblasted on the sample surface through another shadow mask to define a cloverleaf-type geometry. The Hall effect and resistivity measurements were performed using the double ac method[ll, 121, which employs a separate frequency for the exciting current and the magnetic field. The Hall voltage appears at the heterodyne frequencies and can be measured by lock-in techniques. This frequency domain separation of Hall voltage from the zero field voltage allows very small Hall voltages (-10 nV) to be measured. The ac excitation eliminates the various averaging methods normally used to cancel thermoelectric, thermomagnetic, and misalignment errors. The temperature dependences of the Hall effect and resistivity were measured using a coldfingertype liquid nitrogen cryostat wlth a built-in magnet [ 131.A calibrated platinum resistance thermometer was used simultaneously with a chromel-ahunel thermocouple with a digital readout to monitor the sample temperature. The temperature of the coldflnger was varied using resistive heating, and the sample temperature was held constant to *lo while the measurements were taken. The layer removal technique used in this study consisted of repetitively growing a thin anodic oxide layer using a KMnO,-acetone solution[lC 151and then chemically etching the layer in HCl. Tsang[lS] has calibrated the oxide layer thickness to the charge passed through the cell, and we have used this method of depth calibration in this study.
tWork supported by the Joint Services Electronics Program (U.S. Army, U.S. Navy, and U.S. Air Force) under Contract DAABM-72-C-0259,and by MonsantoCompany.
of
Beryllium ion implantation in GaAs has been demonstrated to produce p-type IayQs with good ekctrical
activation[ l] and efficient hnninescence[2] after proper annealing, although controlled Be doping is di5cult by standard diffusion[3] or growth[4] techniques. It has recently been reported that Be ion implantation may be used to fabricate red light-emitting diodes in GaAs,_,P.(x - 0.38)[5] and that proper annealing can result in restructuring of the lattice and excellent optical activation[6]. In this paper we present Hall effect and resistivity measurements on Be implanted GaAs,_, P. (x 0.38) layers. It is shown that annealing at 900°Cwith Si,N, or SiO, encapsulation results in excellent electrical activation of the implanted Be, with a doping efficiency of -100% for Be fluences ~10” ions/cm-’ at 250 keV. The maximum Be concentration for such an implant on the basis of LSS theory[7] is ~2.5 x 1018cm-‘. Temperature dependence of the Hall effect data obtained from Be implanted layers exhibits impurity conduction effects for Be fluences ~6 x 10” ions/cm* at 250 keV. Hall effect measurements performed in conjunction with layer removal by anodic oxidation and chemical stripping of the oxidized layer yields a distribution of the electrically active Be which is very close to that predicted by the LSS theory[7]. This suggests that there is no significant d.iEusion of the implanted Be during the anneal, for a fluence of 6 x 10’”ions/cm’.
961
Figure 1 illustrates the anneal temperature dependence sheet carrier concentration and mobility for
et al. P. K. CHATTEFSEE
962
GaAso.62 P0.g
implanted GaAs,_, P, (x - 0.38), which are consistently lower than those reported here for Be implanted material. However, the quality of the substrate material is extremely important in comparing mobility data, and these differences may reflect better crystal structure of the wafers used in this study, rather than inherent differences between Zn and Be doping. The data presented in Fig. 1 were obtained from samples annealed with S&N, encapsulation. Hall effect measurements on samples annealed with SiO, encapsulation resulted in sheet carrier concentrations and mobilities that were remarkably close (21%) to those obtained with S&N,. This leads us to conclude that the encapsulating dielectric for annealing GaAs,_, P, (x - 0.38) does not determine the activation and lattice restructuring properties as critically as is the case for GaAs[2]. The reason for this difference between GaAs and GaAs,_, P, is unclear. The presence of phosphorus perhaps reduces the tendency of the crystal to form native defects during heat treatment. It may also be argued that since a large density of deep level defects are already present in the GaAs,_, P, crystal[l8], differences in defect generation during anneals with the two encapsulants may be insignificant by comparison.
Be Implant
250 keV 0 6x1014cni2
a 1.1x1014 0 6X1013
TEMPERATURE DEPENDENCE
<
1
1
I
700 800 Anneal Temperature (“C)
9’
Fig. 1. Hall mobility and sheet carrier concentration as a function of isochronal anneal temperature for G~As~.~~P~.~~samples implanted with 250 keV Be to the doses shown.S&N,encapsula-
The temperature variation of Hall mobility in Be implanted GaAs,_,P,(x - 0.38) samples is shown in Fig. 2. The relatively heavy implantation doses used were necessary because of the practical problems associated with making ohmic contacts to lightly doped p -GaAs,_, P,. The temperature dependence of mobility for the doping densities used is similar to that reported in Zn doped GaAs [ 191.The mobility is dominated by lattice scattering 0
r
GaAs0.62 Pose Be Implant 250 keV. 900°C Anneo I
0 fi 0
tion wasusedfor the anneals. GaAs,_,P,(x - 0.38). Samples were Be implanted to various doses and annealed for 1 hr at temperatures between 600 and 900°Cwith Si,N4encapsuiation. The sheet carrier concentration increases with anneal temperature, whereas the mobility is roughly independent of anneal temperature. The maximum value of sheet carrier concentration agrees remarkably well with implantation fluences up to 1.1x 1014ions/cm*. At higher fluences the sheet carrier concentration is lower than the fluence, becoming about 60% of the fluence for a dose of 6 x lOI ions/cm2. Since the maximum impurity concentration for this implantation on the basis of the LSS theory [7] is about 1.5 x lOI cmm3,partial activation is not very surprising. The doping efficiency reported here is significantly higher than that obtained for donor implants in GaAs [ 161. The hole mobility in GaAs,_, P, (x - 0.38) is lower than that in GaAs, presumably due in part to alloy (As, P) disorder in the ternary system. Very little data has been reported for mobilities in p-type GaAs,_,P,. Stoneham [ 171has recently measured Hall mobilities in Zn
160
_ 240 lemperature
,_..,
6x10’+cr%z l.lX10’4 6~10’~
320
L 3
i-K1
Fig. 2. Hall mobility as a function of temperature for GaAs, 62P0.38 samples implanted with 250 keV Be to the doses shown, and annealed at9OOT for 0.5 hr.
963
Electrical properties of Be-implanted GaAs,_,P,
at temperatures above 12O”C,and impurity scattering dominates at lower temperature. The Hall coefficient and resistivity data obtained from these samples show features of impurity banding, as expected for the doping density used. The Hall coefficient reaches a maximum value and then decreases with decreasing temperature. The presence of impurity banding makes it difficult to estimate the binding energy of Be in GaAs,_,P,(x - 0.38). However, the similarity of this data to that reported for Zn doped GaAs indicates that implanted Be serves as a shallow acceptor similar to Zn in this material. Recent photoluminescence measurements on more lightly doped material indicate an acceptor binding energy of 35? 3 meV for Be in GaAs,_,P,(x 0.38)[6]. DEPTHDISTRIBuTlON
Figure 3 presents the distribution of implanted Be obtained from Hall effect measurements in conjunction
with successive anodic oxidation and stripping. The sample was implanted to a fluence of 6 x lOI ions/cm* and annealed at 900°C for 0.5 hr with S&N.,encapsulation. We have also included the depth distribution expected on the basis of LSS theory[7]. For this doping level the measured profile agrees very well with the predicted gaussian distribution. It is clear that very little diffusion of the implanted Be takes place during anneal for a relatively high doping concentration (-10’” cm-“). This result is very significant in the context of device fabrication. It is likely that higher fluences (a1O’4cm-‘) may lead to anomalous Be diffusion as has been observed in heavily doped GaAs[20]. In contrast with results reported here, implanted Zn diffuses rapidly during anneal in this material, even for moderate doping levels. As a result, the electro-optical properties obtained are characteristic of Zn
diffused into the undamaged bulk, and do not indicate the quality of the implanted layer. The electrical activation data presented here are obtained from the implanted layer, since Be does not diffuse significantly, and provide strong evidence of the high crystal quality of these layers. SUMMARY
We have presented Hall effect and resistivity data for Be implanted GaAs,_,P,(x - 0.38). Annealing at 900°C with SiO, or S&N4 encapsulation produces excellent electrical activation of the implanted Be, with a doping efficiency of essentially loo%, for Be doses up to - 10” ions/cm’ at 250 keV. The temperature dependence of mobility shows impurity banding effects typical of heavy acceptor doping. Hall effect measurements in conjunction with thin layer removal by anodic oxidation and stripping indicate that the distribution of implanted Be after anneal is very similar to that predicted by LSS theory, for a fluence of 6 x lOI ions/cm*. Thus, there is no significant diffusion of Be during anneal at this fluence. Multiple energy implants may, therefore, be used to synthesize acceptor profiles suitable for special device applications. For example, it is possible to investigate the effect of various acceptor profiles on the performance of light emitting diodes fabricated in this material[5,21]. Furthermore, observations by scanning electron microscopy [21] indicate negligible lateral diffusion of implanted Be under Si3N4 masks, in contrast with extensive lateral motion of diffused Zn. Be is thus a useful acceptor in GaAs,_,P, for fabrication of devices requiring good electrical activation, special acceptor distributions, and precise lateral dimension control.
Acknowledgements-We
/
1
I
I
I
would like to thank D. L. Keune of Monsanto Co. for providing the crystals for this work.
I
Go%., POza
“Er”
Be 25qlp 6E13 cm 900°C Anneal
m
REFERENCES
1. R. G. Hunsperger, R. G. Wilson and D. M. Jamba, .I. Appl. Phys. 43, 1318(1972). 2. P. K. Chatterjee, K. V. Vaidyanathan, W. V. McLevige and B. G. Streetman, Appl. Phys. Lett. 21, 565 (1975). 3. E. A. Poltoratskii and V. M. Stuchebnikov, Sou. Phys. So/id &ate 8, 770 (1%6).
4. D. J. Ashen, P. J. Dean, D. T. J. Hurle, J. B. Mullin, A. M. White and P. D. Greene, J. Phvs. Chem. So/ids 36. 1041 (1975). 5. P. K. Chatterjee, B. G. Streetman, D. L. Keune and A. H. Herzog, IEEE IEDM Tech. Digest 187(975). 6. P. K. Chatterjee, W. V. McLevige and B. G. Streetman, L Appl. Phys. (1976). To be published. 7. J. Lindhard, M. SchartTand H. Schi#tt, Mat. Fys. Medd. Vid. Schlsk 33, 1 (1963). 8. L. J. van der Pauw, Phillips. Res. Rep. 13, 1 (1958). 9. T. Itoh and Y. Oana, J. Appl. Phys. 44, 4982 (1973). 10. R. Chwang, B. J. Smith and C. R. Crowell, Solid- St. Electron
7 t
17, 121 (1974).
6L 0 Depth
(pm)
1.4 LPll93
Fig. 3. Distribution of implanted Be obtained from differential Hall effect measurements for a GaAh,,P,, sample implanted with 250keV Be to a dose of 6 x 10’”ions/cm2.The Be distribution predicted on the basis of LSS theory[7]is superimposed.
11. B. R. Russell and C. Wahlig,Rev. Sci. Instr. 21,1028(1950). 12. T. Kaneda, S. Kobayashi and K. Shimoda, Jap. J. Appl. Phys. 12, 1335(1973). 13. M. Altwein, H. Finkenrath and T. Stockel, J. Phys. E. 6,623 (1973). 14. E. B. Stoneham, I. Elec&ochem. Sot. 121, 1382(1974). 15. D. Z. Tsang, M. S. Thesis, University of Illinois, 1975.Also,
964
P. K. CHATTERJEE et al.
Coordinated Science Laboratory Report R-708, UILU-ENG, 75-2244(1975).Available from NTIS, Springfield, Virginia. 16. J. F. Gibbons and R. F. Tremain, Jr., Appl. Phys. Lett. 26, 199 (1975). 17. E. B. Stoneham, Tech. Report 4733-l. Stanford Electronics Lab., California (1975). 18. L. Forbes, Solid-St. Electron. 18, 635 (1975).
19. F. Ermanis and K. Wolfstim, I. A@. Phys. 37,1%3 (1966). 20. J. Comas, Naval Research Laboratory, private communication. 21. P. K. Chatterjee, Ph.D. Thesis, University of Illinois (1976); also, Coordinated Science Laboratory Report R-721, UILUENG, 76-2209(1976).