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 (
${N} _{\text {it}}$
) 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 Mg
_0.25
Ca
_0.75
O (MgCaO) and amorphous Al
₂
O
₃
. 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 Al
₂
O
₃
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.