Growth of high-quality 1.93-eV AIGaAs using metalorganic chemical vapor deposition

High-quality Al_xGa_1-xAs with a bandgap of 1.93 eV has been grown using metalorganic chemical vapor deposition (MOCVD). Levels exceeding 10₁₈ cm_-3 can be obtained for Se, Si and Zn dopants. In particular, incorporation of the re-type dopants at this bandgap is not appreciably less efficient than in lower-bandgap Al_xGa_1-xAs. The best material, as measured by photoluminescence intensity, is obtained using high V/III ratios (40 forp-type material and as high as 60 forn- type and low growth rates (300 Å/min). Purification of the arsine in situ with an Al/Ga/In eutectic bubbler to remove trace water and oxygen impurities is found to be essential for the growth of high-quality material, as indicated by photoluminescence intensity measurements. Solar cells fabricated from such material exhibit efficiencies as high as 12.1% under one-sun, airmass zero (AMO) conditions, with an open-circuit voltage of 1.38 V, short-circuit current density of 14.1 mA/cm², and fill factor of 0.84.