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/cm 2 and R 0 A product greater than 1.7x10 6 Ohm.cm 2 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.

Interband optical absorption obtained by pseudopotential method for type-II InAs/GaSb SL photodetectors

“…The SL structure shows close to symmetric behavior where the electrons are delocalized in the conduction miniband of the SL while the holes are localized in the GaSb layer. Therefore, the absorption spectrum shows 2D and 3D characteristics [18]. Besides, there is a large variation between experimental EPM form factors, and offsets reported for different measuring techniques or constituent material values obtained by different researchers.…”

“…Figure5. Calculated absorption coefficient (red line) of 9.5 ML/11 ML (InAs/GaSb) 60 periods unintentionally doped superlattice for 80 K (experimental data shown with the blue circle is extracted from[18]). …”