Growth condition optimization and mobility enhancement through inserting AlAs monolayer in the InP-based InxGa1−xAs/In0.52Al0.48As HEMT structures*

The structure of InP-based InxGa1−xAs/In0.52Al0.48As pseudomorphic high electron mobility transistor (PHEMT) was optimized in detail. Effects of growth temperature, growth interruption time, Si δ-doping condition, channel thickness and In content, and inserted AlAs monolayer (ML) on the two-dimensional electron gas (2DEG) performance were investigated carefully. It was found that the use of the inserted AlAs monolayer has an enhancement effect on the mobility due to the reduction of interface roughness and the suppression of Si movement. With optimization of the growth parameters, the structures composed of a 10 nm thick In0.75Ga0.25As channel layer and a 3 nm thick AlAs/In0.52Al0.48As superlattices spacer layer exhibited electron mobilities as high as 12500 cm2V−1s−1 (300 K) and 53500 cm2V−1s−1 (77 K) and the corresponding sheet carrier concentrations (Ns) of 2.8 × 1012 cm−2 and 2.9 × 1012 cm−2, respectively. To the best of the authors' knowledge, this is the highest reported room temperature mobility for InP-based HEMTs with a spacer of 3 nm to date.