Optically In-situ Monitored Growth Of Carbon Doped Inalas By Lp-movpe Using Cbr_4

摘要

Carbon-doped InAlAs, AlAs and InAs layers have been grown by LP-MOVPE using carbontetrabromide (CBr_4) as the dopant source. Optical in-situ together with ex-situ characterization techniques were used to measure the epilayers growth rate, C and p-type doping level and InAlAs alloy composition. We investigated the influence of growth parameters on C incorporation and on CBr_4 etching effect. Both decrease as the growth temperature or the Ⅴ/Ⅲ ratio increases. The indium content in InAlAs was found to increase with the CBr_4 flow, especially at low Ⅴ/Ⅲ ratio. AlAs and InAs undoped and doped layers, grown using the same growth conditions on GaAs and InAs substrates, respectively, allowed to separately quantify the CBr_4 etching effect on the AlAs and InAs fraction of the InAlAs layers. We found that CBr_4 does not etch AlAs but reacts strongly with the TMAl vapor phase. On the contrary, CBr_4 etches constantly the InAs solid phase, and independently of the TMln flow. These two differences explain consistently the diversity reported in the InAlAs composition variation as a function of CBr_4 flow rate.