The impact of mesa etching method on IR photodetector current-voltage characteristics
Dariusz Smoczyński, Krzysztof Czuba, E. Papis-Polakowska, Pawel Kozłowski, J. Ratajczak, Iwona Sankowska, A. Jasik
Abstract
In the paper, the results of the study on how etching type influences the quality of mesa structures in discrete antimonide-based photodetectors are presented. Devices based on both symmetrical and asymmetrical InAs/GaSb type-II superlattices (T2SLs) designed for mid- (MWIR) and long-wavelength infrared spectral range, respectively were tested. Mesa structures were formed using photolithography followed by wet or inductively coupled plasma – reactive ion etching. The former was based on H3PO4:C4H6O6:H2O:H2O2 solution, and dry etching was performed in BCl3:Ar plasma. The quality of mesas was evaluated using a scanning electron microscope. The current-voltage characteristics of MWIR photodetectors based on the symmetric T2SL show significantly lower leakage currents for plasma etched devices.