Via-hole etching for InGaP/GaAs double heterojunction backside contact solar cells

Backside contact technology has been employed for increasing the efficiency of the solar cells by minimizing the reflectance caused by the metal electrodes. Via-hole etching is one of the key processes for realizing the backside contacts in the inverted InGaP/GaAs double heterojunction solar cells. The via-holes were fabricated by using three-step dry etching process. It involved three different plasma chemistries such BCl 3 /Cl 2 , CH 4 /H 2 and CH 4 /H 2 /Ar to achieve smooth and tapered sidewall profile of the via-holes. After the dielectric insulating layer was deposited on the etched via-holes, the metal contact to reach the front side ohmic contact layer was successfully deposited.