Gan Avalanche Photodiodes Grown By Hydride Vapor-Phase Epitaxy

Avalanche photodiodes have been demonstrated utilizing GaN grown by hydride vapor-phase epitaxy. Spatially uniform gain regions were achieved in devices fabricated on low-defect-density GaN layers that exhibit no microplasma behavior. A uniform multiplication gain up to 10 has been measured in the 320-360 nm wavelength range. The external quantum efficiency at unity gain is measured to be 35%. The electric field in the avalanche region has been determined from high-voltage C-V measurements to be similar to 1.6 MV/cm at the onset of the multiplication gain. Electric fields as high as 4 MV/cm have been measured in these devices. Response times are found to be less than 5 mu s, limited by the measurement system. (C) 1999 American Institute of Physics. [S0003-6951(99)02948-4].