Effect of diffusion and surface recombination on the frequency-dependent characteristics of an OPFET

Abstract

Analytical studies have been made on the effect of diffusion and surface recombination on the frequency dependent characteristics of an ion-implanted GaAs optical field effect transistor. Modulated optical generation and voltage dependent depletion layer width in the active region have been considered whereas photovoltaic effect is ignored in this analysis. Result shows that drain-source current decreases with the increases of modulated signal frequency but diffusion effect increases the modulating frequency range from c.m. to m.m. wavelength. Moreover, I- V changes significantly with the trap center density only when N r >= 10 23 /m 2 with diffusion effect and >= 10 20 /m 2 without diffusion effect at a particular dimension of the device. This model may be very much useful to measure the sensitivity of the device in terms of trap center density and modulating frequency.