TITLE:
Influence of Nonlocality on Amplification of Space Charge Waves in n-GaN Films
AUTHORS:
Volodymyr Grimalsky, Svetlana Koshevaya, Margarita Tecpoyotl-T., Fernanda Diaz-A.
KEYWORDS:
Gallium Nitride, Films, Negative Differential Conductivity, Space Charge Waves, Amplification, Nonlocality
JOURNAL NAME:
Journal of Electromagnetic Analysis and Applications,
Vol.3 No.2,
March
4,
2011
ABSTRACT: It is investigated theoretically the amplification of space charge waves (SCWs) due to the negative differential conduc-tivity (NDC) in n-GaN films of submicron thicknesses placed onto a semi-infinite substrate. The influence of the nonlo-cal dependence of the average electron velocity on the electron energy is considered. The simplest nonlocal model is used where the total electron concentration is taken into account. The relaxation momentum and energy frequencies have been calculated. The influence of the nonlocality on NDC results in the decrease of the absolute value of its real part and appearance of the imaginary part. The calculation of the diffusion coefficient leads to essential errors. The simulations of spatial increments of the amplification of SCWs demonstrate that the nonlocality is essential at the fre-quencies f ? 150 GHz, and the amplification is possible up till the frequencies f ? 400 ??? 500 GHz.