Processing Techniques for Dilute Nitride Gallium Arsenide Intermediate-Band Solar Cell Structures

Abstract

A solar cell processing procedure is calibrated for dilute nitride GaAs intermediate band solar cell structures, and applied to a reference GaAs cell. The processing consists of front and backside contact metalization, a mesa etch, an etch through a heavily doped contact region, a SiNx antire ective coating deposition, and a contact opening etch. The backside contact requires an anneal to become Ohmic. A poor turnout of the processed reference GaAs solar cell and time constraints prohibited processing of actual intermediate band solar cells. The efficiency of the reference cell was unacceptably low and major sources of loss are thought to be due to a high series resistance as well as non-radiative recombination due to Al0.4Ga0.6As oxidation. Sources of series resistance may arise from poor conduction properties of the window and emitter layer of the reference cell, poor quality contacts, and residual SiNx on the contacts. Further measures should be taken to eliminate these problems before processing actual structures.