AlGaN Ultraviolet A and Ultraviolet C Photodetectors with Very High Specific Detectivity D^*

The development of AlGaN pin photodetectors sensitive in the UV range with different narrow band active regions is reported in this paper. Structures were grown by metalorganic vapor phase epitaxy on (0001) sapphire substrates using three-dimensional GaN as well as high temperature AlN nucleation. Very high specific detectivities of 1×10¹⁴ cm Hz^0.5 W^-1 can be achieved based on optimized growth conditions of undoped and doped AlGaN layers with an Al-content ranging from 0% up to 100%. The crack-free AlGaN layers have edge dislocation densities in the range of 5×10⁹ cm^-2. Based on the two different nucleation types, pin layer structures were grown and fabricated to UV-A (320 to 365 nm) and UV-C (< 280 nm) photodetectors. The electro-optical performance of these photodetectors measured on-wafer will be presented in this paper, supplemented by the data of a single photodetector chip mounted in a TO 18 package.