A MBE-grown high-efficiency GaAs solar cell with a directly deposited aluminum front contact

A novel metallization scheme for GaAs p-n solar cells grown by molecular beam epitaxy (MBE) is described. A p/sup +/-GaAs contact layer was grown on top of the AlGaAs window layer, followed by a pure aluminum layer. This MBE-grown aluminum layer serves both as metallization and as self-aligned mask for selective etching down to the AlGaAs window. The solar cell showed an efficiency of about 20%; the I-V characteristics revealed that negligible series resistance was present in the structure. To test the novel p-contact a second sample was grown. Using a transmission-line model (TLM) structure, a metal-semiconductor contact resistance of 1.5*10/sup -2/ Omega -cm/sup 2/ was found.<
>