Evaluation of TMAH treatment for isolation process of N-polar GaN HEMTs

The application of a wet treatment using tetramethylammonium hydroxide (TMAH) is expected to reduce process damage related to dry etching and increase the simplicity of the isolation process of GaN high electron mobility transistors (HEMTs). This study investigates the isolation process using TMAH and fabricates N-polar GaN HEMT devices. Based on the results, there are sufficient resistance values exceeding 10¹¹ Ω between the isolation gaps treated with the TMAH treatment. For the fabricated N-polar GaN HEMTs, values of IDmax = 1.13 A/mm and Ron = 3.5 Ωmm were obtained, demonstrating that the application of TMAH is useful as a device separation technique for N-polar GaN HEMTs.