Study of Undoped and Fe-doped AlGaN/GaN Grown by MOVPE at Low Temperature and High Magnetic Field

• Main Authors: Ying-chieh Wang, 王映傑
• Other Authors: Ikai Lo
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/49vuu4

碩士 === 國立中山大學 === 物理學系研究所 === 97 === We discussed the electronic properties in AlxGa1-xN/GaN heterostructures. There are six different samples of AlxGa1-xN/GaN we prepared for this experiment, three of them are undoped AlxGa1-xN/GaN with different x values which is 0.17, 0.29 and 0.33, respectively. The others are Fe-doped AlxGa1-xN/GaN which the x value is 0.18, 0.19 and 0.21 for each sample. Comparing these two types’ materials’ results, we tried to confirm the impurity’s characteristic in our samples. From the Hall measurement results, carrier concentration of Fe-doped AlxGa1-xN/GaN were pretty lower than undoped AlxGa1-xN/GaN, and the mobility at 4.2 K are almost two times to undoped AlxGa1-xN/GaN. At the same time, we performed Shubnikov-de Hass measurement, and two subbands of the 2DEG were populated on the samples for x value is 0.29 and 0.33. The energy separation for first two subbands is 109meV. We also observed obvious beat pattern in the SdH oscillations due to the spin splitting on the samples and the greatest spin-splitting energy is 5.96meV in our measurement. Furthermore, we observed evident PPC effect on the samples of Fe-doped AlxGa1-xN/GaN, the carrier concentrations increased at least 23% after illumination. Meanwhile the samples of undoped AlxGa1-xN/GaN can just produce 10.7% increment at most.