Eur. Phys. J. B 7, 79-83 (1999)
https://doi.org/10.1007/s100510050590

Nonparabolic multivalley balance-equation approach to impact ionization: Application to wurtzite GaN

China Center of Advanced Science and Technology (World Laboratory) P.O. Box 8730, Beijing 100080, P.R. China State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Metallurgy, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, P.R. China

Received: 27 April 1998
Revised: 17 July 1998
Accepted: 13 August 1998
Published online: 15 January 1999

Abstract

Extended nonparabolic multivalley balance equations including impact ionization (II) process are presented and are applied to study electron transport and impact ionization in wurtzite-phase GaN with a , , and conduction band structure at high electric field up to 1000 kV/cm. Hot-electron transport properties and impact ionization coefficient are calculated taking account of the scatterings from ionized impurity, polar optical, deformation potential, and intervalley interactions. It is shown that, for wurtzite GaN when the electric field approximately equals 530 kV/cm, the II process begins to contribute to electron transport and results in an increase of the electron velocity and a decrease of the electron temperature, in comparison with the case without the II process. Similar calculations for GaAs are also carried out and quantitative agreement is obtained between the calculated II coefficients by this present approach and the experimental data. Relative to GaAs, GaN has a higher threshold electric field for II and a smaller II coefficient.