The electrical properties of bulk GaN crystals grown by HVPE

• The samples investigated in this work are sliced from the same bulk crystal.
• The dislocation density of samples ranges from 2.4×106 cm−2 to 2.3×105 cm−2.
• The evolution of dislocation and impurity with thickness is presented.
• The mechanism determining the electrical properties of bulk GaN is discussed.
• HVPE is identified as an effective approach in growing thick bulk GaN.

The electrical properties of high-quality bulk GaN crystals grown by Hydride Vapor Phase Epitaxy (HVPE) were investigated. The series of samples were sliced from the same bulk crystal grown by HVPE. The crystal quality of the samples was characterized by the cathode luminescence (CL) and high resolution X-ray diffraction measurements (HRXRD), the evaluated dislocation density ranges from 2.4×106 cm−2 to 2.3×105 cm−2. The temperature-dependent Hall measurements were conducted and the results were analyzed theoretically. The results suggest that with low dislocation density (≤106 cm−2) and low carrier concentration (≤1017 cm−3), the impurity concentration should play an important role in the electrical properties. With the impurity concentration decreasing, the hall mobility increases from 619 to 1160 cm2/(V s), and the carrier concentration decreases from 5.42×1016 cm−3 to 1.31×1016 cm−3.