GaN Avalanche Photodectors: A Full Band Monte Carlo Study of Gain, Noise and Bandwidth

This paper presents a theoretical study of the performance of GaN-based avalanche photodetectors using an ensemble Monte Carlo method. The model includes the details of the full band structure derived from nonlocal empirical pseudopotential calculations. Carrier-phonon and impact ionization scattering rates are obtained from the calculated electronic structure and from a first-principles study of the lattice dynamics. Multiplication gain, noise and bandwidth properties of back- and front-illuminated structures are evaluated by means of full band Monte Carlo simulation for different crystal orientations and multiplication region thicknesses. The simulation results indicate that hole injection in devices grown along the Γ-A direction provides the most favorable operating condition in terms of gain and noise. Finally, gain saturation effects due to electric field screening induced by photogenerated carriers are discussed.