Keywords: epitaxial semiconductor films, molecular beam epitaxy, dilute bismides, bismide semiconductor alloys, nanotechnology, molecular beam epitaxy, MBE, gallium arsenide
Growth and properties of the dilute bismide semiconductor GaAs1−xBix a complementary alloy to the dilute nitrides
In this review we describe the growth and properties of the dilute bismide semiconductor alloy GaAs1−xBix and show how its properties are in certain respects complementary to the dilute nitride alloy, GaNyAs1−y. Like the dilute nitrides the dilute bismides show a giant band gap bowing effect in which a small concentration of the alloying element has a disproportionate effect on the band gap, however in the case of the bismide the band gap reduction is associated with an increase in the energy of the valence band maximum (VBM) rather than a reduction in the energy of the conduction band minimum (CBM). Under standard GaAs growth conditions Bi acts as a surfactant with associated improvements in surface quality. In order to incorporate Bi, growth temperatures below 400°C are used with As2/Ga flux ratios close to unity. The electron mobility of GaAs is only weakly affected by Bi alloying, in contrast to the dilute nitrides where the electron mobility decreases rapidly with N alloying. Bi alloying also produces a giant bowing effect in the spin orbit splitting in the valence band. Strong room temperature photoluminescence is observed. Prospects for future device applications of this new compound semiconductor alloy are discussed.