Abstract
In this thesis, the contributions of bulk and structure inversion asymmetry to spin-orbit interaction in two-dimensional system were studied. In the be- ginning, we calculated Dresselhaus parameter ° and Rashba parameter ® of material systems, then theoretically estimated the spin splitting energy ¢0 resulting from bulk inversion asymmetry (BIA) and structure inversion asymmetry (SIA). For Dresselhaus parameter once the structure was grown, it was decided its value. However Rashba parameter changes with the di®er- ence of band structure and carrier density, it can be separated into ‾eld and boundary parts to calculate. In material system 1, wafer 1 and wafer 3 has a doping layer above the 2D channel, but wafer 2 and wafer 4 do below the channel. The 25 nm inserted InP layer inset above the channel for wafer 1 and wafer 2. After calculating, the doping layer position decided the sign of the ‾eld contribution and the inserted InP layer enhanced or reduced the total Rashba parameter depend- ing the doping layer position. It can be observed that for wafer 1 and wafer 3 the contribution to spin splitting energy of SIA is larger than BIA, for wafer 2 due to InP layer the reduction to total Rashba parameter resulted in the SIA spin splitting energy is among two of BIA spin splitting energy of di®erent direction, for wafer4 the SIA splitting energy decreased with a increasing carrier density, especially over ns = 9:3 £ 1011cm¡2, BIA contri- bution is larger than SIA. In material system 2, the lattice mismatch with GaAs material In0:2Ga0:8As was used for 2D quantum well. The front doping and inserted GaAs was pre- sented in order to product a step-like valence band ¡8. The strain e®ect was also considered. The results of our analysis was that the SIA contribution is smaller than BIA even though GaAs inset into the 2D quantum well.