Junction depth measurement in HgCdTe using laser beam induced current (LBIC)

A new, nondestructive junction depth measurement technique for HgCdTe photo voltaic devices is investigated. The technique uses a scanning laser micros cope to obtain laser beam induced current (LBIC) data from which informatio n regarding the junction depth is extracted, and is applicable to both homo junction and heterojunction diodes. For implanted heterojunction photodiode s, the position of the n-p junction relative to the heterojunction is an im portant factor determining completed device performance, with blind photodi odes resulting if the n-p junction is incorrectly placed. At present, the o nly methods available for junction depth determination (e.g., secondary ion mass spectroscopy and differential Hall) are destructive and not applicabl e as routine process monitoring techniques. It is envisaged that the develo pment of a nondestructive routine process monitoring procedure will help im prove yield and reduce the cost of HgCdTe photovoltaic devices. In this pap er, experimental and theoretical results are presented in order to assess t he sensitivity of the new technique to the effects of junction doping densi ty, illumination wavelength, frontside/backside illumination, and test stru cture geometry.