在180-500 K温度范围测量了不掺杂半绝缘GaAs晶体的电阻率和霍耳系数.按结果可把样品分为两类:(一)高阻样品,激活能为0.71-0.64eV,由EL2能级决定;(二)中阻样品,激活能为 0.43 eV和 0.37 eV,由 EL5和 EL6能级决定,这与 Martin 等报道的结果有所不同.热处理实验进一步证实了我们的分析. The resistivity and the Hall coefficient of undoped semi-insulating GaAs crystals were measured over a temperature range of 180-500 K. The samples were divided into two categories according to the results: (i) high-impedance samples with activation energies from 0.71 to 0.64 eV and EL2 energy levels; (b) For the medium resistance samples, the activation energies are 0.43 eV and 0.37 eV, which are determined by the EL5 and EL6 energy levels, which is different from the results reported by Martin et al. Heat treatment experiments further confirm our analysis.