Improved Test Circuit for Characterization of the Dynamic On-Resistance of GaN-HEMTs over a Wide Operating Range

GaN-HEMTs show excellent switching and conduction characteristics and are an excellent candidate to replace Si-based power semiconductors with voltage ratings of up to 650 V. However, trapping phenomena, such as the dynamic on-resistance dR<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds,on</inf>, have not yet been fully eliminated. As these can significantly influence the conduction losses and reliability of GaN-HEMTs, suitable characterization methods are required. This paper presents an improved test circuit to characterize the dynamic on-resistance dR<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds,on</inf> over a wide operating range. This includes positive and negative drain currents I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</inf>, adjustable gate-voltages V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gs</inf> and temperatures T<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf>. In order to stimulate trapping phenomena, the bias voltage on the device under test (DUT) in the off-state V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</inf> is adjustable in magnitude and duration (soak time). In addition, the drain current I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</inf> of the DUT only flows for the duration of the measuring interval, which leads to less self-heating. For an improved measurement of the drain-source voltage V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</inf> in the on-state, an improved clamp-circuit was developed. With small modifications to the test circuit, switching characteristics can also be measured.