Moss-Burstein and plasma reflection characteristics of heavily doped n-type InxGa1-xAs and InPyAs1-y

Degenerately doped (> 10(19) cm(-3)) n-type InxGa1-xAs (x similar to 0.67) and InPyAs1-y (y similar to 0.65) possess a number of intriguing electrical and optical properties relevant to electro-optic devices and thermophotovoltaic devices in particular. Due to the low electron effective mass of these materials (m*< 0.2) and the demonstrated ability to incorporate n-type dopants into the high 10(19) cm(-3) range, both the Moss-Burstein band gap shift and plasma reflection characteristics are particularly dramatic. For InGaAs films with a nominal undoped band gap of 0.6 eV and N=5x10(19) cm(-3), the fundamental absorption edge increased to 1.27 eV. InPAs films exhibit a shorter plasma wavelength (lambda(p)similar to 5 mu m) in comparison to InGaAs films (lambda(p)similar to 6 mu m) with similar doping concentrations. The behavior of the plasma wavelength and the fundamental absorption edge are investigated in terms of conduction band nonparabolicity and Gamma-L valley separation using detailed band structure measurements and calculations. (C) 1999 American Institute of Physics. [S0021-8979(99)01612-6].