Methodology for the Study of Dynamic ON-Resistance in High-Voltage GaN Field-Effect Transistors

Abstract

Abstract-We have developed a new methodology to investigate the dynamic ON-resistance (R ON ) of high-voltage GaN field-effect transistors. The new technique allows the study of R ON transients after a switching event over an arbitrary length of time. Using this technique, we have investigated dynamic R ON transients in AlGaN/GaN high-voltage, high electron-mobility transistors over a time span of ten decades under a variety of conditions. We find that right after an OFF-to-ON switching event, R ON can be several times higher under dc conditions. The increase in R ON is enhanced as the drain-source voltage in the OFF-state increases. The R ON recovery process after an OFF-to-ON switching event is characterized by a fast release of trapped charge through a temperature-independent tunneling process followed by conventional thermally activated detrapping on a longer timescale. After a high-power-to-ON switching event, in contrast, detrapping only takes place through a temperature-independent process. We postulate that the fast temperature-independent detrapping originates from interface states at the AlGaN barrier/AlN spacer interface. The thermally activated detrapping can arise from traps at the surface of the device or inside the AlGaN barrier. These findings are relevant in the quest to engineer a reliable GaN power switch with minimum dynamic R ON problems.

GaN-HEMT dynamic ON-state resistance characterisation and modelling

“…According to the results presented by authors in [3], GaN device R DS(on) values would increase by a maximal factor of 4 after 1ms bias time depending on bias V DS voltage value. The results presented by authors in [4] demonstrate that device R DS(on) values would further increase 50% if bias time is doubled. In the on-state (low bias), detrapping occurs and the R DS(on) values decrease to the steady state value at a rate characterised by the detrapping time.…”

“…There are mainly two different methods to measure GaN-HEMT dynamic R DS(on) values: one method is by using directly a measurement equipment [4], and another one is by using an electrical circuit, where different circuit topologies are proposed by authors in [3], [5]- [8]. In this paper, a new characterisation circuit is presented to measure GaN-HEMT dynamic R DS(on) values, which could be easily implemented.…”

Modelling and quantification of power losses due to dynamic on-state resistance of GaN E-mode HEMT

“…The introduction of new packaging with lower stray inductance allows for further development of compact power conversion systems using these new components. On the other hand, charge trapping phenomenon in the HEMT structure that negatively affects the device performance have been documented [1], [2]. The phenomenon is known as current collapse or dynamic on-state resistance (dynamic R DS,on ) leading to increased on-state resistance in the GaN HEMT channel.…”

“…The increase in on-state resistance is highest immediately after the device is turned on and it returns to the rated resistance value after a certain time period. The magnitude and time constant of the increase has been shown to be dependent on both device design and operational parameters [2], [3], [4], [5].…”

“…The dynamic R DS,on adds a loss component which currently is not accounted for during the design phase. There are several authors who have investigated the phenomenon with operation parameters close to that in actual application [2], [3], [4], [5], [6], [7], [8]. Examples of operation parameters include bias voltage, device blocking time, current, and temperature variation.…”