Electrical doping of HgCdTe by ion implantation and heat treatment

Abstract The use of ion implantation to make junctions in HgCdTe is of increasing interest because the technique can be applied to the manufacture of infrared photovoltaic detectors, which are used for the development of focal plane array devices with a large number of pixels. For these devices, control of the doping of HgCdTe and of the building of junctions is of major importance. Using the technique of ion implantation, n-p diodes have been made in previous work using irradiation damage for the formation of an n+-doped surface region on p substrates. In more recent work, n-on-p and p-on-n diodes were successfully achieved by activation of implanted impurities after annealing of irradiation damage using indium or arsenic ions. The control of the electrical doping of the HgCdTe substrate is also very important for devices because the intrinsic properties of diodes are directly related to it. During post-implant anneals or technological heat treatment the acceptor concentration (mercury vacancies) may increase or decrease and this parameter has to be controlled throughout the process. Furthermore, this effect may have interactions on junction formation mechanisms, the annealing of defects, impurity redistribution, etc. The production of very high quality devices using ion implanted n-p junctions made in HgCdTe epilayers has been demonstrated and results obtained using ion implantation junction formation techniques are given to illustrate of device feasibility.