- Email: [email protected]
Rapid thermal annealing of arsenic implanted relaxed Si1−xGex
s
Nuclear Instruments
and Methods in Physics Research B 120 ( 1996) 161~ 164
__
. __
MIMI
B
Beam Interactions with Materials&Atoms
I!!!3
ELSEVIER
Rapid thermal annealing of arsenic implanted relaxed
, _.yGe,
Larsen a’*, S.Yu. Shiryaev a, P. Gaiduk b, V.S. Tishkov b
A. Nylandsted
a /n,sfi~r~te of Phy.sics h The Institute
Si
Jbr Physics
und A,stronomy.
Proh1em.s.
Unioer.tity
Belorussian
oJ’Aurhu.s.
Stute Uniurrsity.
DK-8000 Kurchutou
Actrhus .a.
C. Demnurk
7. 220106
Minsk.
Be1oru.s
Abstract The electrical activity and redistribution during rapid thermal annealing (RTA) of high concentrations of As implanted into epitaxially grown, relaxed Si, _ ,Ge r for x I 0.5 have been studied as a function of composition x and RTA parameters. At a given RTA temperature the maximum carrier concentration decreases and the redistrubution increases with increasing .Y. Maximum carrier concentrations and junction depths as a function of composition and RTA parameters are given.
I. Introduction
2. Experimental
Relaxed, epitaxial Si,_ ,Ge, alloy layers grown on (100) Si substrates are new and exiting materials which are expected to play a significant role in future Si-based microelectronics [I]. They are grown e.g. by molecular beam epitaxy (MBEl or chemical vapour deposition (CVD) [2]. Until recently, layers of thick Si, _ ,Ge, layers of arbitrary x grown on (100) Si contained very high concentrations of dislocations; however, with the introduction of the compositional grading technique layers of high crystalline quality of arbitrary composition can be grown
Relaxed. epitaxial Si, _.IGe.r alloy layers of Ge composition .Y= 0.15, 0.25, 0.45, and 0.50 were grown by molecular beam epitaxy (MBE) on (100) Si substrates using the compositional grading technique [3]. A silicon buffer layer of thickness I pm was first grown followed by the growth of a compositionally graded buffer layer with a grading rate of 10% Ge/pm. The thickness of the top uniform layer was 2 pm in each case and the samples were either p-type doped with boron or n-type doped with Sb, in both cases to a concentration of - 3 X IO” cm-’ The substrate temperature during growth was always 800°C. Growth conditions identical to the above have previously been demonstrated to result in epitaxial layers of high structural and electrical quality [IO, I I]. Arsenic was implanted at room temperature to a dose of 8 X lOI cm- 2; during implantation the samples were tilted by an angle of 7” to avoid channeled implantations along the (100) directions. in order to achieve the same As peak concentration of - 9 X 10” cm-’ in the different alloys, implantation energies between 160 and 177 keV were chosen. With these implantation parameters projected ranges of - 1000 A and longitudinal stragglings of - 300 A are obtained. In the n-type epitaxial layers a deep boron implantation was done in order to electrically separate the arsenic-implanted layer from the remainder of the alloy layer. Subsequently, the samples were annealed by RTA in an argon ambient at temperatures between 700 and 1050°C for a time of I5 s. Carrier density profiles were measured by differential Hall effect/resistivity measurements on van der Pauw structures using anodic oxidation and stripping. The calibration of the depth scale was done by measuring the thickness of the removed layer using a Dektak 3030 surface profiler. In each measuring step a layer of - 100 .& was removed.
[31. Implantation of As in Si combined with rapid thermal annealing (RTA) is widely used in modem microelectronics [4] and can be foreseen to be used also to dope SiGe-alloy layers. Only a few investigations have been reported on ion implantation into epitaxial, relaxed SiGe alloy layers. Most of these investigations were concerned with solid phase epitaxy of implantation-induced amorphous layers [5-7] or with ion implantation-induced defect structures 18.91. To our knowledge only a single paper has been concerned with the electrical activity of ion implanted impurities in relaxed SiGe epitaxial layers, namely ion implantation of Sb combined with furnace annealing [IO]: peak carrier concentrations of 4 X 10” cm- ’ were observed for .Y< 0.35. The present paper on the redistribution and electrical activity of high concentrations of ion implanted As in relaxed Si , _ .,Ge, for .r 5: 0.50 combined with rapid thermal annealing contains the first results of a more comprehensive investigation of ion implantion of electrically active impurities in relaxed SiGe alloys.
Corresponding [email protected]. 0168-583X/96/$15.00 P/I
SOl68-583X(96)00500-9
author.
Fax:
Copyright
+ 45-8612-0740;
email:
0 1996 Elsevier Science B.V. All rights reserved
procedure
162
A. Nylundsted
Larsen et ul./Nucl.
Instr. und Mrth.
in Phys. Rex. B I20 (1996) 161-164
4x10zo,
3. Results and discussion Characteristic carrier-density profiles after RTA at different temperatures are shown in Fig. I. There are two effects which catch the eye in this annealing-temperature range. Firstly, the peak-carrier concentration is not very sensitive to the annealing temperature but is to the composition, and secondly, the redistribution in the x = 0.50 alloy is much more pronounced than in the x = 0.15 alloy. Fig. 2 shows the peak-carrier concentration as a function of RTA temperature for the different compositions. The general tendencies observed are firstly an almost constant peak-carrier concentration for a given composition for RTA temperatures below u 900°C and secondly a decrease in the peak-carrier concentration with increasing x at a given temperature. In general, the peak-carrier concentration of high concentration, ion implanted As in Si after RTA reflects two different phenomena [ 121: at low anneal temperature a supersaturated solution is obtained;
1
ioo 1,
,.1,.,.I,,,,I.,,./,..~
700 Anneal
800
900
Temperature
1000
1100
(“C)
Fig. 2. Peak-carrier concentrations of As implanted to a dose of 8 X lOI cm-’ determined by differential Hall/resistivity measurements as a function of rapid thermal annealing temperature for x=0 (0). x=0.15 (O), x=0.25 (0). x=0.45 (B), and x=0.50(0~.
‘02’
(a)
0
1000
3000
2000 Depth
4000
(A)
lo*’(b)
I”
0
1000
2000 Depth
3000
4000
(A)
Fi g. 1. Carrier-density profiles of As implanted to a dose of 8x IO’s cme2 into (a) S&&e,,,, at an energy of 170 keV and at an energy of 177 keV. The profiles were (b) % &e,.s, determined by differential Hall/resistivity measurements. Rapid thermal annealings were done at the already-mentioned condi-
with increasing temperature this supersaturated concentration is reduced towards the equilibrium-carrier concentration; however, the equilibrium-carrier concentration increases with temperature and the net result is a behaviour with a minimum in the peak-carrier concentration at around 800°C as observed in Fig. 2 for x = 0. The significant reduction in peak-carrier concentration observed for x = 0.15 and 0.25 at temperatures above 900°C is probably correlated to an onset of GeAs-precipitate formation as has been observed previously [8]. The peak-carrier concentrations at temperatures higher than 800°C for x = 0 are in agreement with published values [ 121; according to Trumbore [ 131 the solubility of As in Ge is lower than in Si at a given temperature, hence, the observed decrease of the peak-carrier concentration with increasing x is in agreement with expectations. The degree of electrical activation of As in Si, _.IGe, as a function of temperature is shown in Fig. 3. The increase in activation with increasing temperature as observed in the figure is not a result of an increase in peak-carrier concentration as discussed above but merely reflects the increase in redistribution with increasing temperature. This is one more example demonstrating that one should not critically use the measured changes of the degree of activation as an indication of changes in peakcarrier concentration. The redistribution of As as a function of RTA temperature for the different alloy compositions is demonstrated in Fig. 4. As a measure of the redistribution the diffusion length at the concentration of 5 X lOI cm-j is used. From studies of As redistribution in Si, in which chemical and carrier density profiles have been compared 1141, it was concluded that for concentrations below the maximum-carrier concentration the chemical and carrier-density
A. Nylunclsted Lorsm
I’ “”
et ctl./Nucl.
Instr. unrl Mrth. in Phys. Rr.s. B 120 (1996) 161-164
““‘1
“““’ /I’
,’ -._o/’
/
7’
*/
1’
I’
o.._
x---x
0” 2
_... ,.-.. 0’ I’ 25
/’ t
lC
600
700
I
. . . . . . ..I
800
900
1000
1100
Temperature (“C) Fig. 3. Electrically active fraction of As as a function of rapid thermal annealing temperature for x = 0 (O), x = 0.15 (X), and I = 0.45 (e). The electrically active fraction is determined as the ratio between the total electrically active concentration determined by differential Hall/resistivity measurements and the total chemical concentration determined by integrating the ion current during the ion-implantation process.
profiles are identical; in the present case the peak-carrier concentration is always significantly higher than 5 X IO’” cm-‘, hence the diffusion length at 5 X lOI cm -’ is considered a good measure of the redistribution. It appears from the figure. as a general tendency, that the redistribution increases with increasing Ge content. The temperature dependence for a given composition is well represented by an Arrhenius expression in the whole temperature range. Assuming that the diffusion length 1 depends on the diffusion coefficient D as I - D’/2, the same activation energy of diffusion of 2.7 eV with an uncertainty of about 25% is found for all the compositions. The diffusion is expected to be strongly concentration dependent in the
163
present case of extreme extrinsic diffusion for a given composition, with a distribution of activation energies which for silicon is known to cover the range from - 2 eV for the highest carrier concentration to - 3.5 eV for the lowest [ 151; in addition, the low activation energy for As diffusion in Ge of - 2.2 eV 1161 will gradually come into play with increasing Ge content. As a result the diffusion of high concentration of As in these SiGe alloys is expected to be very complicated and the value of 2.7 + 0.7 eV observed in the present investigation cannot be used to differentiate between the different diffusion mechanism in play; more precise values are needed for that. Recently, studies have been performed of in-growth doped, low concentration Sb in relaxed, MBE- grown Si,_ rGer for x I 0.5 [I?]. Also in that case a strong enhancement in the diffusivity was observed with increasing Ge content.
4. Conclusions Carrier-density profiles measured by differential Hall/resistivity measurements have been used to characterized the effect of RTA on high concentrations of As implanted into epitaxially grown, relaxed Sir ,Ge., for x I 0.5. The peak-carrier concentration is found to be rather insensitive to the RTA temperature for temperatures below - 900°C but sensitive to the composition; the maximum carrier concentration is found to vary between 3.6 X IO” cmmi for .Y= 0 obtained after RTA at 900°C and 0.9 X IO” cm-” for x = 0.50 obtained after RTA at 750°C. The As redistribution is strongly dependent on the Ge content showing an increasing redistribution with increasing Ge content. For a given composition the temperature dependence of the redistribution follow an Arrhenius expression.
Acknowledgements This study was supported by the NATO Linkage Grant No. 940672 and by the EU Human Capital and Mobility programme through the Ion Beam Processing of Semiconductors (IBOS) Network. Thanks are due to J. Lundsgaard Hansen for the MBE growths.
References [I] Y.-H. Xie, E.A. Fitzgerald,
so0
700
800
900
Anneal Temperature Fi g. 4. Redistribution annealing temperature
1000
1100
(‘C)
of As as a function of rapid thermal for x = 0 (0). x = 0.15 (0). x = 0.25 (0 ), x = 0.45 cm), and x = 0.50 (v).The degree of redistribution is determined as the diffusion length at a concentration of 5X lOI cmm3.
D. Monroe. G.P. Watson and P. Silverman, Jpn. J. Appl. Phys. 33 (1994) 2372. [2] See e.g. K. Eberl and W. Wegscheider, in: Handbook on Semiconductors. Vol. 3A, Materials, Properties and Preparation, ed. S. Mahajan (Not&Holland, Amsterdam, 1994) p. 595. [31 E.A. Fitzgerald, Y.-H. Xie, D. Monroe, P.J. Silverman, J.M. Kuo, A.R. Kortan, F.A. Thiel and B.E. Weir, J. Vat. Sci. Technol. B IO (1992) 1807.
164
A. Nylatulsted
Larsen et al./Nucl.
[4] See e.g. R.B. Fair, ed., in: Rapid Thermal
[5] [6] [7] [8] [9]
[IO]
Instr. and Meth. in Phys. Res. B 120 (1996) 161-164
Processing, Science and Technology (Academic Press, San Diego, 1992) p. 169. S.Y. Shiryaev, M. Fyhn and A. Nylandsted Larsen, Appl. Phys. Lett. 63 (19931 3476. P. Kringhoj, R.G. Elliman. M. Fyhn, S.Y. Shiryaev and A. Nylandsted Larsen, Nucl. Instr. and Meth. B 106 (I 995) 346. T.E. Haynes, M.J. Antonell, C. Archie Lee, and KS. Jones, Phys.Rev. B 5 1 (I 995) 7762. V.S. Tishkov, P.I. Gaiduk, S.Yu. Shiryaev and A. Nylandsted Larsen, Appl. Phys. Lett. 68 (1995) 655. A. Nylandsted Larsen, C. O’Raifeartaigh, R.C. Barklie, B. Holm, F. Priolo, G. Lulli, R. Bianconi, J. Lindner, F. Cristiano and P.L.F. Hemment, to be published. C. O’Raifeartaigh, A. Nylandsted Larsen, F. Cristiano and P.L.F. Hemment, Appl. Phys. A 61 (1995) 579.
[I I] A. Nylandsted Larsen, J. Lundsgaard Hansen, R. Schou-Jensen, S.Y. Shiryaev, P. Riis 0stergaard. J. Hartung, G. Davies, F. Jensen and J. Wulff Petersen, Physica Scripta T 54 (1994) 208. [12] A. Nylandsted Larsen, B. Christensen and S.Yu. Shiryaev, J. Appl. Phys. 71 (1992) 4854. [13] F.A. Trumbore, Bell Syst. Tech. 39 (1960) 205. [14] A. Nylandsted Larsen, S.Yu. Shiryaev, E. Schwartz Sorensen and P. Tidemand-Petersson, Appl. Phys. Lett. 48 (19861 1805. [15] A. Nylandsted Larsen, K. Kyllesbech Larsen, P.E. Anderson and B.C. Svensson, J.Appl. Phys. 73 (19931 691. [ 161 B.L. Sharma, Defect Diff. Forum 70-71 (I 990) 1. [17] A. Nylandsted Larsen and P. Kringhoj, Appl. Phys. Lett. 68 (I 996) 2684.
Nuclear Instruments
and Methods in Physics Research B 120 ( 1996) 161~ 164
__
. __
MIMI
B
Beam Interactions with Materials&Atoms
I!!!3
ELSEVIER
Rapid thermal annealing of arsenic implanted relaxed
, _.yGe,
Larsen a’*, S.Yu. Shiryaev a, P. Gaiduk b, V.S. Tishkov b
A. Nylandsted
a /n,sfi~r~te of Phy.sics h The Institute
Si
Jbr Physics
und A,stronomy.
Proh1em.s.
Unioer.tity
Belorussian
oJ’Aurhu.s.
Stute Uniurrsity.
DK-8000 Kurchutou
Actrhus .a.
C. Demnurk
7. 220106
Minsk.
Be1oru.s
Abstract The electrical activity and redistribution during rapid thermal annealing (RTA) of high concentrations of As implanted into epitaxially grown, relaxed Si, _ ,Ge r for x I 0.5 have been studied as a function of composition x and RTA parameters. At a given RTA temperature the maximum carrier concentration decreases and the redistrubution increases with increasing .Y. Maximum carrier concentrations and junction depths as a function of composition and RTA parameters are given.
I. Introduction
2. Experimental
Relaxed, epitaxial Si,_ ,Ge, alloy layers grown on (100) Si substrates are new and exiting materials which are expected to play a significant role in future Si-based microelectronics [I]. They are grown e.g. by molecular beam epitaxy (MBEl or chemical vapour deposition (CVD) [2]. Until recently, layers of thick Si, _ ,Ge, layers of arbitrary x grown on (100) Si contained very high concentrations of dislocations; however, with the introduction of the compositional grading technique layers of high crystalline quality of arbitrary composition can be grown
Relaxed. epitaxial Si, _.IGe.r alloy layers of Ge composition .Y= 0.15, 0.25, 0.45, and 0.50 were grown by molecular beam epitaxy (MBE) on (100) Si substrates using the compositional grading technique [3]. A silicon buffer layer of thickness I pm was first grown followed by the growth of a compositionally graded buffer layer with a grading rate of 10% Ge/pm. The thickness of the top uniform layer was 2 pm in each case and the samples were either p-type doped with boron or n-type doped with Sb, in both cases to a concentration of - 3 X IO” cm-’ The substrate temperature during growth was always 800°C. Growth conditions identical to the above have previously been demonstrated to result in epitaxial layers of high structural and electrical quality [IO, I I]. Arsenic was implanted at room temperature to a dose of 8 X lOI cm- 2; during implantation the samples were tilted by an angle of 7” to avoid channeled implantations along the (100) directions. in order to achieve the same As peak concentration of - 9 X 10” cm-’ in the different alloys, implantation energies between 160 and 177 keV were chosen. With these implantation parameters projected ranges of - 1000 A and longitudinal stragglings of - 300 A are obtained. In the n-type epitaxial layers a deep boron implantation was done in order to electrically separate the arsenic-implanted layer from the remainder of the alloy layer. Subsequently, the samples were annealed by RTA in an argon ambient at temperatures between 700 and 1050°C for a time of I5 s. Carrier density profiles were measured by differential Hall effect/resistivity measurements on van der Pauw structures using anodic oxidation and stripping. The calibration of the depth scale was done by measuring the thickness of the removed layer using a Dektak 3030 surface profiler. In each measuring step a layer of - 100 .& was removed.
[31. Implantation of As in Si combined with rapid thermal annealing (RTA) is widely used in modem microelectronics [4] and can be foreseen to be used also to dope SiGe-alloy layers. Only a few investigations have been reported on ion implantation into epitaxial, relaxed SiGe alloy layers. Most of these investigations were concerned with solid phase epitaxy of implantation-induced amorphous layers [5-7] or with ion implantation-induced defect structures 18.91. To our knowledge only a single paper has been concerned with the electrical activity of ion implanted impurities in relaxed SiGe epitaxial layers, namely ion implantation of Sb combined with furnace annealing [IO]: peak carrier concentrations of 4 X 10” cm- ’ were observed for .Y< 0.35. The present paper on the redistribution and electrical activity of high concentrations of ion implanted As in relaxed Si , _ .,Ge, for .r 5: 0.50 combined with rapid thermal annealing contains the first results of a more comprehensive investigation of ion implantion of electrically active impurities in relaxed SiGe alloys.
Corresponding [email protected]. 0168-583X/96/$15.00 P/I
SOl68-583X(96)00500-9
author.
Fax:
Copyright
+ 45-8612-0740;
email:
0 1996 Elsevier Science B.V. All rights reserved
procedure
162
A. Nylundsted
Larsen et ul./Nucl.
Instr. und Mrth.
in Phys. Rex. B I20 (1996) 161-164
4x10zo,
3. Results and discussion Characteristic carrier-density profiles after RTA at different temperatures are shown in Fig. I. There are two effects which catch the eye in this annealing-temperature range. Firstly, the peak-carrier concentration is not very sensitive to the annealing temperature but is to the composition, and secondly, the redistribution in the x = 0.50 alloy is much more pronounced than in the x = 0.15 alloy. Fig. 2 shows the peak-carrier concentration as a function of RTA temperature for the different compositions. The general tendencies observed are firstly an almost constant peak-carrier concentration for a given composition for RTA temperatures below u 900°C and secondly a decrease in the peak-carrier concentration with increasing x at a given temperature. In general, the peak-carrier concentration of high concentration, ion implanted As in Si after RTA reflects two different phenomena [ 121: at low anneal temperature a supersaturated solution is obtained;
1
ioo 1,
,.1,.,.I,,,,I.,,./,..~
700 Anneal
800
900
Temperature
1000
1100
(“C)
Fig. 2. Peak-carrier concentrations of As implanted to a dose of 8 X lOI cm-’ determined by differential Hall/resistivity measurements as a function of rapid thermal annealing temperature for x=0 (0). x=0.15 (O), x=0.25 (0). x=0.45 (B), and x=0.50(0~.
‘02’
(a)
0
1000
3000
2000 Depth
4000
(A)
lo*’(b)
I”
0
1000
2000 Depth
3000
4000
(A)
Fi g. 1. Carrier-density profiles of As implanted to a dose of 8x IO’s cme2 into (a) S&&e,,,, at an energy of 170 keV and at an energy of 177 keV. The profiles were (b) % &e,.s, determined by differential Hall/resistivity measurements. Rapid thermal annealings were done at the already-mentioned condi-
with increasing temperature this supersaturated concentration is reduced towards the equilibrium-carrier concentration; however, the equilibrium-carrier concentration increases with temperature and the net result is a behaviour with a minimum in the peak-carrier concentration at around 800°C as observed in Fig. 2 for x = 0. The significant reduction in peak-carrier concentration observed for x = 0.15 and 0.25 at temperatures above 900°C is probably correlated to an onset of GeAs-precipitate formation as has been observed previously [8]. The peak-carrier concentrations at temperatures higher than 800°C for x = 0 are in agreement with published values [ 121; according to Trumbore [ 131 the solubility of As in Ge is lower than in Si at a given temperature, hence, the observed decrease of the peak-carrier concentration with increasing x is in agreement with expectations. The degree of electrical activation of As in Si, _.IGe, as a function of temperature is shown in Fig. 3. The increase in activation with increasing temperature as observed in the figure is not a result of an increase in peak-carrier concentration as discussed above but merely reflects the increase in redistribution with increasing temperature. This is one more example demonstrating that one should not critically use the measured changes of the degree of activation as an indication of changes in peakcarrier concentration. The redistribution of As as a function of RTA temperature for the different alloy compositions is demonstrated in Fig. 4. As a measure of the redistribution the diffusion length at the concentration of 5 X lOI cm-j is used. From studies of As redistribution in Si, in which chemical and carrier density profiles have been compared 1141, it was concluded that for concentrations below the maximum-carrier concentration the chemical and carrier-density
A. Nylunclsted Lorsm
I’ “”
et ctl./Nucl.
Instr. unrl Mrth. in Phys. Rr.s. B 120 (1996) 161-164
““‘1
“““’ /I’
,’ -._o/’
/
7’
*/
1’
I’
o.._
x---x
0” 2
_... ,.-.. 0’ I’ 25
/’ t
lC
600
700
I
. . . . . . ..I
800
900
1000
1100
Temperature (“C) Fig. 3. Electrically active fraction of As as a function of rapid thermal annealing temperature for x = 0 (O), x = 0.15 (X), and I = 0.45 (e). The electrically active fraction is determined as the ratio between the total electrically active concentration determined by differential Hall/resistivity measurements and the total chemical concentration determined by integrating the ion current during the ion-implantation process.
profiles are identical; in the present case the peak-carrier concentration is always significantly higher than 5 X IO’” cm-‘, hence the diffusion length at 5 X lOI cm -’ is considered a good measure of the redistribution. It appears from the figure. as a general tendency, that the redistribution increases with increasing Ge content. The temperature dependence for a given composition is well represented by an Arrhenius expression in the whole temperature range. Assuming that the diffusion length 1 depends on the diffusion coefficient D as I - D’/2, the same activation energy of diffusion of 2.7 eV with an uncertainty of about 25% is found for all the compositions. The diffusion is expected to be strongly concentration dependent in the
163
present case of extreme extrinsic diffusion for a given composition, with a distribution of activation energies which for silicon is known to cover the range from - 2 eV for the highest carrier concentration to - 3.5 eV for the lowest [ 151; in addition, the low activation energy for As diffusion in Ge of - 2.2 eV 1161 will gradually come into play with increasing Ge content. As a result the diffusion of high concentration of As in these SiGe alloys is expected to be very complicated and the value of 2.7 + 0.7 eV observed in the present investigation cannot be used to differentiate between the different diffusion mechanism in play; more precise values are needed for that. Recently, studies have been performed of in-growth doped, low concentration Sb in relaxed, MBE- grown Si,_ rGer for x I 0.5 [I?]. Also in that case a strong enhancement in the diffusivity was observed with increasing Ge content.
4. Conclusions Carrier-density profiles measured by differential Hall/resistivity measurements have been used to characterized the effect of RTA on high concentrations of As implanted into epitaxially grown, relaxed Sir ,Ge., for x I 0.5. The peak-carrier concentration is found to be rather insensitive to the RTA temperature for temperatures below - 900°C but sensitive to the composition; the maximum carrier concentration is found to vary between 3.6 X IO” cmmi for .Y= 0 obtained after RTA at 900°C and 0.9 X IO” cm-” for x = 0.50 obtained after RTA at 750°C. The As redistribution is strongly dependent on the Ge content showing an increasing redistribution with increasing Ge content. For a given composition the temperature dependence of the redistribution follow an Arrhenius expression.
Acknowledgements This study was supported by the NATO Linkage Grant No. 940672 and by the EU Human Capital and Mobility programme through the Ion Beam Processing of Semiconductors (IBOS) Network. Thanks are due to J. Lundsgaard Hansen for the MBE growths.
References [I] Y.-H. Xie, E.A. Fitzgerald,
so0
700
800
900
Anneal Temperature Fi g. 4. Redistribution annealing temperature
1000
1100
(‘C)
of As as a function of rapid thermal for x = 0 (0). x = 0.15 (0). x = 0.25 (0 ), x = 0.45 cm), and x = 0.50 (v).The degree of redistribution is determined as the diffusion length at a concentration of 5X lOI cmm3.
D. Monroe. G.P. Watson and P. Silverman, Jpn. J. Appl. Phys. 33 (1994) 2372. [2] See e.g. K. Eberl and W. Wegscheider, in: Handbook on Semiconductors. Vol. 3A, Materials, Properties and Preparation, ed. S. Mahajan (Not&Holland, Amsterdam, 1994) p. 595. [31 E.A. Fitzgerald, Y.-H. Xie, D. Monroe, P.J. Silverman, J.M. Kuo, A.R. Kortan, F.A. Thiel and B.E. Weir, J. Vat. Sci. Technol. B IO (1992) 1807.
164
A. Nylatulsted
Larsen et al./Nucl.
[4] See e.g. R.B. Fair, ed., in: Rapid Thermal
[5] [6] [7] [8] [9]
[IO]
Instr. and Meth. in Phys. Res. B 120 (1996) 161-164
Processing, Science and Technology (Academic Press, San Diego, 1992) p. 169. S.Y. Shiryaev, M. Fyhn and A. Nylandsted Larsen, Appl. Phys. Lett. 63 (19931 3476. P. Kringhoj, R.G. Elliman. M. Fyhn, S.Y. Shiryaev and A. Nylandsted Larsen, Nucl. Instr. and Meth. B 106 (I 995) 346. T.E. Haynes, M.J. Antonell, C. Archie Lee, and KS. Jones, Phys.Rev. B 5 1 (I 995) 7762. V.S. Tishkov, P.I. Gaiduk, S.Yu. Shiryaev and A. Nylandsted Larsen, Appl. Phys. Lett. 68 (1995) 655. A. Nylandsted Larsen, C. O’Raifeartaigh, R.C. Barklie, B. Holm, F. Priolo, G. Lulli, R. Bianconi, J. Lindner, F. Cristiano and P.L.F. Hemment, to be published. C. O’Raifeartaigh, A. Nylandsted Larsen, F. Cristiano and P.L.F. Hemment, Appl. Phys. A 61 (1995) 579.
[I I] A. Nylandsted Larsen, J. Lundsgaard Hansen, R. Schou-Jensen, S.Y. Shiryaev, P. Riis 0stergaard. J. Hartung, G. Davies, F. Jensen and J. Wulff Petersen, Physica Scripta T 54 (1994) 208. [12] A. Nylandsted Larsen, B. Christensen and S.Yu. Shiryaev, J. Appl. Phys. 71 (1992) 4854. [13] F.A. Trumbore, Bell Syst. Tech. 39 (1960) 205. [14] A. Nylandsted Larsen, S.Yu. Shiryaev, E. Schwartz Sorensen and P. Tidemand-Petersson, Appl. Phys. Lett. 48 (19861 1805. [15] A. Nylandsted Larsen, K. Kyllesbech Larsen, P.E. Anderson and B.C. Svensson, J.Appl. Phys. 73 (19931 691. [ 161 B.L. Sharma, Defect Diff. Forum 70-71 (I 990) 1. [17] A. Nylandsted Larsen and P. Kringhoj, Appl. Phys. Lett. 68 (I 996) 2684.