Crystallization of high-resistivity Zn-doped GaN monocrystal via hydride vapor phase epitaxy

Abstract

Recently, high-resistive GaN has been studied for lateral power devices. Fe-doped GaN has high resistivity at room temperature. However, the resistivity becomes lower at high temperatures than at room temperature. Therefore, alternative dopants for GaN have been investigated to achieve resistivity higher than Fe-doped GaN at high temperatures. Several studies on the resistivity of Zn-doped GaN substrates have been conducted; however, single-layered Zn-doped GaN prepared via hydride phase epitaxy (HVPE) has not been investigated. In this study, the monocrystals of Zn-doped GaN were obtained via HVPE using Zn vapor as the dopant precursor and single-layered Zn-doped GaN substrates were fabricated by removing the starting GaN substrates. The concentration of Zn was controlled by changing the temperature of Zn metal, and two Zn-doped GaN substrates with Zn concentrations of 4 × 1017 cm−3 and 1 × 1018 cm−3 were obtained. The dependence of resistivities of the Zn-doped GaN on temperature was measured by the Hall effect method. From 500 K to 930 K, the resistivity of the Zn-doped GaN with the Zn concentration of 4 × 1017 cm−3 varied from 3 × 109 Ωcm to 5 × 102 Ωcm and that with the Zn concentration of 1 × 1018 cm−3 varied from 1 × 1010 to 1 × 105 Ωcm. These values were higher than Fe-doped GaN with almost the same concentration as the Zn-doped GaN. Therefore, Zn-doped GaN could be more preferable for power devices than Fe-doped GaN.