Development of GaAs space solar cells by high growth rate MOMBE/CBE

Realization of high-quality GaAs photovoltaic materials and devices by meta lorganic molecular beam epitaxy (MOMBE) and chemical beam epitaxy (CBE) wit h growth rates in excess of 3 mu m/h is demonstrated. Despite high growth r ates, the optimization of III/V flux-ratio and growth temperatures leads to a two-dimensional layer-by-layer growth mode characterized by a (2 x 4) RH EED diagrams and strong intensity oscillations. The not intentionally doped layers exhibit low background impurity concentrations and good luminescenc e properties. Both n (Si) and p (Be) doping studies in the range of concent rations necessary for photovoltaic device generation are reported. Prelimin ary GaAs (p/n) solar cells fabricated at growth rates in excess of 3 mu m/h exhibit performances comparable to state of the art and stress the potenti al of the high growth rate MOMBE/CBE as reduced toxicity alternatives for t he production of space III-V solar cells. (C) 2000 Elsevier Science B.V. Al l rights reserved.