Study of radiative recombination influence in GaN and GaAs bipolar transistor structures

The influence of radiative recombination and photon recycling in GaAs and 2H-GaN bipolar transistor structures are studied by numerical ID drift-diffusion simulation and by extension of traditional transistor amplification theory. Relying on available data providing for GaN one order of magnitude higher radiative recombination coefficient and absorption coefficients than for GaAs, it has been shown that the radiative recombination may reduce drastically achievable current gain of GaN bipolar transistors. The formulae for radiative recombination dominated current gain in the case of low and high injection level in a transistor base are proposed.