Chemical beam epitaxy of InGaAsN films for multi-junction tandem solar cells

Abstract

Chemical beam epitaxy (CBE) offers a new growth technique for InGaAsN films that are expected to provide the third cell in an ultra-efficiency 4-junction tandem III–V solar cell. In the CBE system, the selection of arsenic (As) and nitrogen (N) sources is important, so the decomposition processes of As (TBAs, TDMAAs) and N (DMHy, MMHy) precursors were investigated with substrate temperature. Both tertiarybutylarsine (TBAs) and trisdimethylaminoarsenic (TDMAAs) were decomposed at a low temperature (<300 °C). While methyl alkyl and tertiarybutyl radical were produced by decomposition of TBAs, Dimethylamine and Aziridine were produced during the decomposition of TDMAAs. The residual carbon concentration in GaAs films grown with TDMAAs was less than 10 16 cm −3. The incorporation of N in GaAsN films grown with DMHy and MMHy decreased with increasing substrate temperature, and the incorporation of N in GaAsN films grown with MMHy was higher.