New planar process for implementation of p-on-n HgCdTe heterostructure infrared photodectors

We report on a new, simple process to fabricate planar Hg1-xCdyTe/Hg1-xCdxTe heterostructure photodiodes with p-on-n configuration. The material used for this demonstration was a double-layer p-on-n heterostructure that was grown by a liquid-phase-epitaxy technique. The p-on-n planar devices consisted of an arsenic-doped p-type cap epilayer on top of a long-wavelength IR n-type active epilayer. The ion-beam-miling p-type conversion effect was used to delineate the active device element, and to isolate the planar device. Detailed analysis of the current characteristics of these diodes as a funciton of temperatuer, show that they have high performance, and that their dark current is diffusion-limited down to 60 K. The results show that over a wide range of cut-off wavelengths, the RoA product values are close to the theoretical limit. Light Beam Induced Current technique was used to characterize the lateral and vertical dimensions of the ion beam milling induced junction. Electro-optic properties of a 2D array of small diodes with a 40-μm pitch are presented, and demonstrate the potential of the new process for implementation of 2D arrays.