InAs/GaSb superlattice pin photodiode: choice of the SL period to enhance the temperature operation in the MWIR domain

Abstract

In this communication, we studied the influence of the SL period on the electrical performances of MWIR pin photodiodes, fabricated by MBE on p-type GaSb substrate. These SL structures are made of symmetric or asymmetric SL period designs and exhibited cut-off wavelength around 5μm at 77K. Experimental measurements carried out on several SL pin photodiodes show the superiority, in terms of dark current density, of the asymmetric SL structure composed of 7 InAs monolayers (MLs) and 4 GaSb MLs. As a result, the 7/4 SL diode exhibits dark current density values as low as 40nA/cm² and R₀A product greater than 1.7x10⁶ Ohm.cm² at 77K, one decade larger than the value obtained with equivalent symmetric 10/10 SL diode. This result obtained demonstrates the strong influence of the SL period design on the performances, and then on temperature operation, of MWIR SL photodiodes.