Investigation of temperature dependent threshold voltage variation of Gd2O3/AlGaN/GaN metal-oxide-semiconductor heterostructure

Abstract

Temperature dependent threshold voltage (Vth) variation of GaN/AlGaN/Gd2O3/Ni-Au structure is investigated by capacitance-voltage measurement with temperature varying from 25°C to 150°C. The Vth of the Schottky device without oxide layer is slightly changed with respect to temperature. However, variation of Vth is observed for both as-deposited and annealed device owing to electron capture by the interface traps or bulk traps. The Vth shifts of 0.4V and 3.2V are obtained for as-deposited and annealed device respectively. For annealed device, electron capture process is not only restricted in the interface region but also extended into the crystalline Gd2O3 layer through Frenkel-Poole emission and hooping conduction, resulting in a larger Vth shift. The calculated trap density for as-deposited and annealed device is 3.28×1011∼1.12×1011 eV−1cm−2 and 1.74×1012∼7.33×1011 eV−1cm−2 respectively in measured temperature range. These results indicate that elevated temperature measurement is necessary to characterize GaN/AlGaN heterostructure based devices with oxide as gate dielectric.

GaN-based power devices: Physics, reliability, and perspectives

“…where q is the electronic charge, A is the area of the capacitor, Gm,max is the peak value of conductance, ω = 2πf where f is the measurement frequency, Cox is the capacitance in accumulation region and Cm is the capacitance corresponding to Gm,max. This method has been successfully applied to the characterization of GaN based devices [496], [497], in which the G-V measurement [494] relies upon the assumption that energy losses and leakage currents in dielectrics are negligibly small [498]. To this end, quasi-static capacitance-voltage (QSCV) measurement [499] is rarely used in AlGaN/GaN HEMTs, because of the high leakage current associated with the Schottky gate [312].…”

“…HFCV measurements performed at room temperature (RT) may not be adequate to characterize wide bandgap GaN and AlGaN interfaces [503] because of the extremely long time constants of deep interface traps. In fact, said deep levels are frozen at RT, thus requiring elevated temperature C-V measurement to accurately characterize the interfaces quality [496]. Recent papers pointed out that the conductance method may show limitations on AlGaN/GaN metal-insulatorsemiconductor capacitors, and discussed the related implications [504] Other papers [505] proposed methodologies to analyze the interface state density of dielectric/GaN MIS devices.…”

Temperature-induced instability of the threshold voltage in GaN-based heterostructure field-effect transistors

“…As to the HFETs, it was observed that the threshold voltage both decreased (−1.6 mV/°C and −1 mV/°C) [7,8] and increased (2 mV/°C) [9] with increased temperature. Similarly, the MOSHFETs exhibited threshold voltage that also decreased (−10 mV/°C and −5 mV/°C) [10,11] or increased (30 mV/ °C and 10 mV/°C) [12,13] with increased temperature. It should be noted that the devices and the gate insulators reported on in these studies were produced using different processing procedures.…”

“…Therefore, static measurement is more appropriate. Various papers report on the static measurement of the temperature-induced instability of the threshold voltage in AlGaN/GaN-based HFETs and MOSHFETs [7][8][9][10][11][12][13]. A relatively small influence of temperature on the threshold voltage is observed in HFETs, which contrasts with MOSHFET counterparts where threshold voltage changes remarkably with temperature.…”

Improved quasi‐physical zone division model with analytical electrothermal Ids model for AlGaN/GaN heterojunction high electron mobility transistors

“…The fundamental properties of GaN HEMTs that are affected by temperature mainly consist of the Schottky barrier height ϕ B , the band gap energy E g , the low-field mobility μ 0 , the maximal electron saturated velocity υ sat , and the heat conductivity k. One way to study the temperature effects on GaN HEMTs performance with regard to these properties is carried out involving solution of complicated numerical expressions. [5][6][7][8] However, these numerical simulations are very time consuming and difficult to incorporate in circuit simulators. In comparison, analytical model is preferred as it is length (L g ) in order to minimize the parasitic gate resistance.…”