Mercury cadmium telluride implanted junction profile measurement and depth control

Abstract

In this work, a novel junction profile measurement method is proposed. A serial of junctions were fabricated by B+ implantation. Then a beveled bar which was about 10mm long and several micrometers deep was formed by carefully controlled wet-etching. The remaining depth of n region changes from the full depth that is about 5.3mm after ion implantation to zero depending on its lateral position and the slope of the etching bar. Voltage-current and Laser Beam Induced Current (LBIC) measurements were applied to determine the HgCdTe junction edge. The LBIC signal orrectification characteristic indicates the existence of a PN junction. The junction depth is extracted from the position where the PN junction disappears and the slope of the etching bar. The junction depth of intrinsic doped HgCdTe was measured, which is about 2.4μm. A significant 0.4mm thick N-region was observed. Moreover, junction depths of samples annealed for different time were also investigated. By this method, it's possible to measure the three dimensional profile of a planar PN junction.Key words： HgCdTe, infrared focal plane arrays (IRFPAs), junction profile, laser beam induced current (LBIC)

Reflow flip-chip bonding technology for infrared detectors

“…The p-n junction of the MCT IRFPA is particularly sensitive to temperatures and even traditional post-implantation annealing can raise problems, such as altered surface conditions [10], and presence of defects and deviation from stoichiometry [11], all of which might be related to Hg movement [12].…”