Analysis of the GaSb-p+/GaSb-p/GaSb-n+/GaSb-n structure performances at room temperature, for thermo-photovoltaic applications

In this paper a GaSb-p+/GaSb-p/GaSb-n+/GaSb-n structure destined for thermo-photovoltaic applications at room temperature was fabricated by Molecular Beam Epitaxy (MBE) technique, in a Varian gen II solid-source machine. At direct bias, the J(V) characteristics of this structure in the dark and under light conditions, have been studied by numerical simulation and compared to the experimental measurements. The spectral response (SR) of the device has been also calculated and examined. For simulation we have used AMPS-1D software program to examine the effect of three parameters like the front contact barrier height (ϕb0) (barrier at metal/GaSb-p+ layer interface), the doping concentration (Na) in the GaSb active region and the thickness (d) of this same layer. Our numerical calculations show that the experimental and simulated J(V) characteristics under dark and light conditions are in good agreement when ϕb0 is equal to 0.24 eV and Na of about 1015 cm−3. These later values of ϕb0 and Na with an active zone thickness of 3 μm give the best results for the cell's external parameters, like the short circuit current (JSC  = 19.21 mA/cm2), the open circuit voltage (VOC  = 0.23 V), the fill factor (FF = 0.67) and the efficiency (Eff = 3%).