High C-doping of MOVPE grown thin Al x Ga 1−x As layers for AlGaAs/GaAs interband tunneling devices

High hole concentrations in LP-MOVPE grown GaAs and AlGaAs layers can be achieved by intrinsic C-doping using TMGa and TMAl as carbon sources. Free carrier concentrations exceeding 1020 cm−3 were realised at low growth temperatures between 520–540°C and V/III ratios <1.2. The C-concentration increases significantly with the Al-content in AlxGa1−xAs layers. We observed an increase in the atom- and free carrier concentration from 5·1019 cm−3 in GaAs to 1.5·1020 cm−3 in Al0.2Ga0.8As for the same growth conditions. Interband tunneling devices with n-type Si and p-type C-doped AlGaAs layers and barriers made of Al0.25Ga0.26In0.49P have been investigated.