OPTICAL AND STRUCTURAL QUALITY OF GAAS EPILAYERS FROM GALLIUM, BISMUTH MIXED-SOLVENTS BY LIQUID-PHASE EPITAXY

Liquid phase epitaxy (LPE) of GaAs epilayers grown at 645 degrees C wa s studied for different Bi compositions in Ga solvent. Mixed solvents such as Ga+Bi were used to improve GaAs epilayer quality. The grown la yers wore characterized by photoluminescence (PL) and etch pit density (EPD) measurements. The Bi composition was varied from 0 to 100% in G a. Good quality epilayers were obtained for 100% Bi composition. PL in vestigations revealed that the epilayer grown using equal atomic perce ntage of Ga and Bi had good crystallinity, which is comparable with th e 100%-Ga-grown epilayer. The PL measurements reveal that carbon inclu sion in the epilayer grown using 50% Ga and 50% Bi solution is compara bly less than other solvent compositions. The EPD was reduced to more than half order of magnitude when the solvent was changed from Ga to B i. The EPD results of epilayers grown using mixed solvents are reporte d for the first time. The EPD of the GaAs epilayer grown using 50% Ga and 50% Bi solution is markedly reduced compared to the other Ga+Bi mi xed solvents, and it is almost equal to the EPD of 100%-Bi-grown epila yers.