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

Abstract

In this article, we report on the single pulse charge pumping (SPCP) measurements as a method to extract the interface trap density ( ${N} _{\text {it}}$ ) 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 Mg0.25 Ca0.75O (MgCaO) and amorphous Al2O3. The signature charge pumping (CP) current peaks are observed enabling a direct extraction of ${N} _{\text {it}}$ as low as $1.4\times 10^{{11}}$ 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 ${N} _{\text {it}}$ by the MgCaO gate stack compared to Al2O3 only gate stack is also confirmed by the SPCP method. SPCP realizes a direct ${N} _{\text {it}}$ 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.