Negligible carrier freeze-out facilitated by impurity band conduction in highly p-type GaN

摘要: Highly p-type GaN films with hole concentrations exceeding 6 × 1019 cm−3 grown by metal-modulated epitaxy are electrically characterized. Temperature-dependent Hall effect measurements at cryogenic temperatures reveal minimal carrier freeze-out in highly doped samples, while less heavily samples exhibited high resistivity and donor-compensated conductivity as is traditionally observed. Effective activation energies low 43 meV were extracted, a maximum Mg efficiency of 52% was found. In addition, the effective energy found to be negatively correlated concentration. These results indicate onset Mott-Insulator transition leading impurity band conduction.