Single Pulse Charge Pumping Measurements on GaN MOS-HEMTs: Fast and Reliable Extraction of Interface Traps Density

In this article, we report on the single pulse charge pumping (SPCP) measurements as a method to extract the interface trap density (N_it) on the GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs). The electron capture and emission processes are monitored in the time domain and studied during the rising and falling edges of a gate voltage pulse. Two different gate stacks are studied by SPCP including epitaxial Mg_0.25 Ca_0.75O (MgCaO) and amorphous Al₂O₃. The signature charge pumping (CP) current peaks are observed enabling a direct extraction of N_it as low as 1.4× 10¹¹ cm^-2 with gate voltage sweeping from OFF-state to ON-state in the GaN MOS-HEMT with epitaxial MgCaO gate stack. A significant reduction of N_it by the MgCaO gate stack compared to Al₂O₃ only gate stack is also confirmed by the SPCP method. SPCP realizes a direct N_it measurement on GaN transistors and confirms the high quality interface between the single crystalline epitaxial MgCaO and GaN. It is verified as a fast and reliable interface characterization method on III-V HEMTs, gate-all-around nanowire transistors, and 2-D transistors, which do not exhibit body contacts as the conventional Si transistors needed for conventional CP measurements.