Modeling and optimization of InGaAs infrared photovoltaic detectors

The performance of InxGa1−xAs detectors operating in the 2–3.4 μm spectral range and temperature of 300 K has been analyzed theoretically as a function of wavelength, band gap and doping level with special emphasis on 2–2.5 μm and 3–3.5 μm atmospheric window devices. The calculations show that the dominant generation–recombination mechanism in p-type, intrinsic and in a lightly doped n-type InGaAs is the spin split-off band Auger process (AS). Since the AS generation increases with the square of the hole concentration, the minimum thermal generation and the best performance can be obtained using moderately doped n-type material as the absorber region of a photovoltaic device. In principle, the ultimate performance can be achieved in the optimized homojunction devices with relatively thick n-type absorber region forming n–p junction with a thin p-type material. N-type doping of absorber region of InGaAs photodiodes at 300 K changes from 1×1014 to 5.2×1015 cm−3 for devices optimized for operation at 2 and 3.4 μm wavelength, respectively.