Characterization of traps and trap-related effects in recessed-gate normally-off AlGaN/GaN-based MOSHEMT

Abstract

Traps and trap-related effects in recessed-gate normally-off AlGaN/GaN-based MOSHEMT with SiO 2 gate dielectric were characterized. Hysteresis in I D -V G was observed at elevated temperature (~120 o C) due to the traps. To understand the traps, current transient in drain was investigated at given gate and drain pulses with different temperatures. Two groups of time constants were extracted: one is nearly constant and the other is decreased with temperature. Extracted activation energies from the drain current transients with temperature are 0.66 eV and 0.73 eV, respectively, for given gate and drain pulses. Using extracted exponential trap density profile from frequency dependent conductance method [4], we could understand C-V behavior with frequency. It was shown that traps inside AlGaN layer are a main cause for the decrease of capacitance at high frequency in inversion region. The pulsed I-V characteristics also show frequency dependence. IntroductionThe AlGaN/GaN high electron mobility transistor (HEMT) is one of the strong candidates for next-generation power and microwave devices [1]. Recently, the metal-oxide-semi conductor heterostructure field-effect transistor (MOSHFET) using the recessed-gate was proposed to reduce the gate current and realize the normally-off characteristics [2]. However, problems of dispersion effects and instabilities due to the presence of traps still prevent the wide usage of this new device. Previously, various methods have been used to study the electrical traps in AlGaN/GaN HEMTs. However, relatively few studies have been made about the traps and trap-related effects in AlGaN/GaN MOSHFETs with a recessed-gate. In this paper, we investigate the traps and trap-related effects in recessed-gate AlGaN/GaN MOSHFETs using various characterization methods including the current transient spectroscopy, frequency dependent conductance method, C-V, and pulsed I-V [3], [4].

Frequency-dependent C-V Characteristic-based Extraction of Interface Trap Density in Normally-off Gate-recessed AlGaN/GaN Heterojunction Field-effect Transistors

“…The FDCMbased D it (E) was also compared with the CM-based D it (E) as shown in Fig. 5 , which is consistent with the previous works [1,6,8,14,15]. In comparison with CM, the proposed FDCM gives abundant information on critical parameters, such as…”

“…A high D it is well known to be affecting the degradation of response time, trap effect of current transient, frequency dispersion, mobility, subthreshold swing and low frequency noise [8]. Several methods such as deep-level transient spectroscopy (DLTS) [9], conductance method (CM) [6], and differential ideality factor technique (DIFT) [10], have been employed in extracting D it .…”

Mechanisms of thermally induced threshold voltage instability in GaN-based heterojunction transistors

“…1), as two predominant types of III-N power devices featuring insulated gate structures, are encountered with challenges of V TH instability originating from the interface traps at the gate-dielectric/III-N interface. [2][3][4] With thermally sensitive electron emission processes of the interface traps, V TH -thermal-stability of MIS-HEMTs 5,6 and MOSCHEMTs is of particular interest, yet has not been adequately investigated.…”

Impact and Origin of Interface States in MOS Capacitor with Monolayer MoS2 and HfO2 High-k Dielectric

“…In particular, the electrical characteristics such as capacitance-voltage ( C-V ) frequency dispersion and its dependence on interface states density18 ( D it ) which influence the carrier transport properties deserve a further investigation. Apart from the mobility and on/off ratio, high D it could also degrade the performance of transistor in terms of response time, traps effect on current transient, subthreshold swing and low frequency noise1920. For methods including mechanical exfoliation (ME), CVD and thermal evaporation, the atomic defects in MoS 2 monolayer have been systematically investigated by J. Hong et al 21…”