Dynamic Control of AlGaN/GaN HEMT Characteristics by Implementation of a p-GaN Body-Diode-Based Back-Gate

Abstract

We report on the implementation of dynamic body-bias technique to improve the performance of AlGaN/GaN high electron mobility transistors (HEMTs) with the successful integration of body-diode. In this configuration, p-GaN body-diode-based back-gate control is used to shift the threshold voltage and dynamically modulate the ON/OFF characteristics of a normally-ON AlGaN/GaN HEMT. A fourth back-gate terminal is connected to the p-GaN layer to control the depletion width of the body-diode, which in turn modulates the 2-D electron gas (2DEG) density. A positive/negative shift in the threshold voltage is measured by increasing/decreasing the depletion width below the channel. A positive back-gate bias application in the ON-state is shown to increase the 2DEG current density resulting in higher ON-current. The application of a negative back-gate bias is shown to be effective in the positive shift of the threshold voltage, in reducing the 2DEG channel current and in increasing the OFF-state break-down voltage. We have experimentally demonstrated enhanced effect of body-diode-based back-gate control in shifting the threshold voltage of a normally-ON HEMT toward normally-OFF mode. The optimum back-gate voltage range which can be applied during both ON and OFF states has been experimentally determined.INDEX TERMS AlGaN/GaN HEMT, dynamic body-biasing, body-diode, back-gate, threshold voltage shift.

Hillock assisted p-type enhancement in N-polar GaN:Mg films grown by MOCVD

“…The gallium nitride (GaN)-based material system and its ternary and quaternary alloys with aluminum (Al) and indium (In) are widely employed in light emitting diodes (LEDs), photodetectors [1][2][3] , and the next generation of power devices [4][5][6][7] . Due to the lack of inversion symmetry within the III-Nitride wurtzite crystal structure the material exhibits a spontaneous polarization charge along the c-direction.…”

Monolithic Integrated AlGaN/GaN Power Converter Topologies on High‐Voltage AlN/GaN Superlattice Buffer

“…Known back-gating effects are classified into static back-gating effects such as lateral channel current reduction at negative substrate bias, [15,16] including a current polarity dependence, [17] excessively increased static vertical leakage at positive substrate bias, [18] and dynamic effects such as crosstalk [19][20][21] dynamically increased on-resistance, [22][23][24] and effects on the effective device capacitances and gate charge [25][26][27] and threshold voltage shift. [28] Advanced isolation techniques such as GaN-on-silicon-oninsulator (SOI) [20,29,30] or back surface isolation techniques [31] have been successfully realized and avoid the substrate biasing effects by local substrate-to-source termination of integrated devices. However, the improved isolation is realized in a trade-off with increased substrate capacitances (in case of additional thin buried oxides in GaN-on-SOI), increased thermal resistance from additional oxide layers, or the risk of silicon p-n-junction conduction.…”

MOCVD Growth and Characterization of Be-Doped GaN

“…Over the last 3 decades, GaN has become an invaluable material for lighting and power management applications. − Much of the success enjoyed by GaN is due to the realization of p-type doping, originally by Amano et al However, despite more than 30 years of development, impurity-doped p-type III-nitrides still suffer from limited carrier concentration and low mobility. Mg, the only widely used and presently viable p-type dopant in III-N, is relatively deep, with a level at ∼160 meV from the valence band edge in GaN .…”