Determination of Suitable Indicators of AlGaN/GaN HEMT Wafer Quality Based on Wafer Test and Device Characteristics

This study investigates various tests on AlGaN/GaN high electron mobility transistor (HEMT) wafers, including photoluminescence spectroscopy, secondary ion mass spectroscopy, X-ray diffraction (XRD), and Hall measurement. The AlGaN/GaN HEMT wafers are grown on low-resistivity Si substrates with various growth conditions for the buffer and channel layers. Characteristics of AlGaN/GaN HEMTs including drain lag, dynamic R_ON, and current transients were measured and correlated with the results from the wafer level tests. Results indicate that epitaxial wafers with low yellow luminescence (YL) to band edge (BE) and blue luminescence (BL) to BE ratios as well as a low carbon concentration but a similar low full width at half maximum of XRD profiles can result in devices with significant suppression of current collapse and the same on-state device characteristics. Therefore, both YL/BE and BL/BE values combined with the carbon concentration in wafer level tests are suitable indicators for estimating device performance.