Comment on the paper entitled “characterization of the interface states at AlGaAs Schottky barriers with a thin interface layer”

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27, No. 12. p. 1157. 1984

LETTERS TO THE EDITOR Comment on the paper entitled “Characterization of the interface states at Al-GaAs Schottky barriers with a thin interface layer” (Received

22 December 1983)

Morante et a/.[11 report the characterization of interface states at Al-nGaAs Schottky barriers. We want to remark that the same measurements and interpretation were already published before[2]. Indeed, from the deviation of the Mott-Schottky relationship under forward bias, we determined a capacitance C,U due to interface states. The frequency dependence of C,” could bc expressed by: CT = The voltage

dependence

cf-‘.

was found

data in close agreement with ours. We want also to point out that our study also included Au-n GaAs, Sn-n and p type GaAs Schottky barriers.

(1) to be:

logC,“=c’V/.

(2)

the formulas derived by Nicollian and Using Goetzberger[3], we determined e. N, as a function of E,“EF. Following the same way Morante et al. [1] obtained

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REFERENCES

1. J. R. Morante, A. Lousa, J. E. Carceller and J. L. Morenza, Solid-St. Electron. 26, 537 (1983). 2. R. L. Van Meirhaeghe, W. H. Laflere, Yu-Min Li and F. Cardon. J. Phvs. D: Am/. Phvs. 14, 1505 (1981). 3. E. N. Nicollian and A. ‘Goetzbkrger, ‘Eer/. S&f. Techn. J. XLVI, 6, 1055 (1967). R. L. VAN MEIRHAEGHE,W. H. LAFLERE, Lahoratorlum voor Kr~stallogra$e en Studie van de Vaste StoJ Rljhsuniversiteit Gent Krijgslaan 281. B-9000 Gent. Belgium.

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Vol 27. No. 12. p 1157. 1984

Reply to comment on “Characterization of the interface states at Al-GaAs barriers with a thin interface layer” (Received

17 February

In the paper referred to above, our previous analysis[l, 21 of the admittance of a P + N junction with a deep level was extended to the investigation of interface states in Schottky barriers. We feel happy that our results were in agreement with the conclusions of the work of R. L. Van Meirhaeghe ef al.[3]. However, we believe that the deduction of information about the interface states from the gN#$u, values is not advisable owing to the possible dependence of CTon the electric field at the interface[4], the energetic position in the gap[5], or the existence of a non-constant surface states distribution[6, 7]. This should explain the dependence on the applied voltage of the gN,c” values found by van Meirhaeghe et 01. [3]. In any case, for a complete confirmation of this model it would be necessary to undertake a more extensive analysis of the deviation of the capacitance from the Mott-Schottky law at different voltages and frequencies, taking the temperature as a parameter.

1157

Schottky

1984) REFERENCES

1. J. R. Morante, J. E. Carceller, P. Cartujo and J. Barbolla, Solid-St. Electron. 26, 1 (1983). 2. J. E. Carceller, P. Cartujo, J. R. Morante, J. C. Brabant and M. Brousseau, Revue Phys. Appl. 15, 843 (1980). 3. R. L. Van Meirhaeghe, W. H. Laflere, Yu-Min Li and F. Cardon, J. Phys. D: Appl. Phys. 14, 1505 (1981). 4. T. C. Poon and H. C. Card, J. Appl. Phys. 51, 6273 (1980). 5. H. Hasegawa and T. Sawada, J. Vat. Sci. Technol. 21, 457 (1982). 6. R. J. Singh and R. S. Srivastava, Solid-St. Electron. 26, 319 (1983). 7. K. Yamasaki and T. Sugano, Appl. Phys. Lett. 35, 933 (1979). Catedra de Electronica Facultad & Fisica Diagonal 645. Barcelona-28.

J. R. MORANTE Spain