金属有机物化学气相沉积生长GaN薄膜的室温热电特性研究

Room-temperature thermoelectric properties of Ga N thin films grown by metal organic chemical vapor deposition

采用金属有机物化学气相沉积技术生长了不同掺杂浓度的Ga N薄膜,并且通过霍尔效应测试和塞贝克效应测试,表征了室温下Ga N薄膜的载流子浓度、迁移率和塞贝克系数.在实验测试的基础上,计算了Ga N薄膜的热电功率因子,并且结合理论热导率确定了室温条件下Ga N薄膜的热电优值(ZT).研究结果表明:Ga N薄膜的迁移率随着载流子浓度的增加而减小,电导率随着载流子浓度的增加而增加;Ga N薄膜材料的塞贝克系数随载流子浓度的增加而降低,其数量级在100—500μV/K范围内;Ga N薄膜材料在载流子浓度为1.60×1018cm-3时,热电功率因子出现极大值4.72×10-4W/m K2;由于Si杂质浓度的增加,增强了Ga N薄膜中的声子散射,使得Ga N薄膜的热导率随着载流子浓度的增加而降低.Ga N薄膜的载流子浓度为1.60×1018cm-3时,室温ZT达到极大值0.0025.

The GaN thin films with different doping concentrations are grown by metal organic chemical vapor deposition. Carrier concentrations, mobilities and Seebeck coefficients of the CaN thin films are measured by Hall and Seebeck system at room temperature. The power factor and the thermoelectric figure of merit are calculated by experimental and theoretical data. The mobility and Seebeck coefficient of GaN thin film decrease with the increase of carrier concentration. The conductivity of GaN thin film increases with the increase of carrier concentration. The Seebeck coefficient of GaN thin film varies from 100 to 500 μV/K, depending on carrier concentration. The highest power factor is 4.72 × 10-4 W/mK2 when the carrier concentration is 1.60 ×1018 cm-3. The thermal conductivity of CaN thin film decreases with the increase of carrier concentration due to the increase of phonon scattering. The largest thermoelectric figure of merit of the GaN thin film at room temperature is 0.0025 when the carrier concentration is 1.60 × 1018 cm-3.