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The voltage dependence of the low-frequency noise of GaN/AlGaN HEMTs is usually modeled in terms of mobility fluctuations. Noise measurements in commercial devices before and after proton irradiation and/or voltage stress have been found instead to be more consistent with number fluctuations. Low-frequency noise measurements vs. temperature show defect-related peaks in energy at ∼ 0.2 eV, ∼ 0.5 eV,...
A novel enhance-mode (normally-off) AlGaN/GaN HEMT structure is proposed and demonstrated. Concretely, a few nanometers of tunnel dielectric as well as several split floating gates (FGs) are inserted beyond the conventional MIS structure of the normally-on counterpart. The FGs are applied to storage negative charges by means of tunneling effect, thereby converting the HEMT to an enhancement mode....
In this work, we report a feasible compact solution to enhance the dynamic performance of GaN-on-Si power devices by integrating a photon source into the drain terminal of a heterojunction field-effect transistor (FET). Photons can be generated from the photonic-ohmic drain (POD) synchronously with turning on of the channel current. These on-chip generated photons can optically pump the electron traps,...
In recent years, GaN power HEMTs are gaining acceptance in power electronic applications. However, the implementation of Class D audio power amplifiers application using GaN power HEMTs has not been widely studied. This paper studies the performance of two open-loop 25 W Class D audio power amplifiers with GaN and silicon output stages using a Pulse Density Modulation (PDM) scheme. Comparisons of...
A simple and effective method to grow GaN on Si substrates has been achieved. The method that GaN comes out from a submicron and deep hole with nearly zero dislocations above the mask is demonstrated. This work proves that reducing the epitaxy area by using mask and increasing the depth to width ratio of pattern contribute to filtering the dislocations and improving the quality of GaN.
Trapping effects still limit the application of GaN-based high-electron mobility transistors (HEMTs). This paper further characters traps in GaN HEMTs based on the drain current transients. A hybrid transient, which contains more valuable information of traps than the single trapping or detrapping transient was detected and analyzed. Three traps with different time constants were determined and their...
A double-π equivalent circuit model well-fitted for on-chip inductors with GaN process is presented in this paper. The equivalent circuit is made up of two cells and can feature the frequency-dependent characteristics well in a wide range of frequency up to 20GHz. The parameter extraction is conducted based on the improved characteristic function method according to four parts. The validation includes...
An efficient approach to engineering the Al2O3/GaN positive interface fixed charges (Qit+) by post-dielectric annealing in nitrogen is demonstrated. The remarkable reduction of interface fixed charges from 1.44×1013 to 3×1012 cm−2 was observed, which leads to a record high threshold voltage (VTH) of +7.6 V obtained in the Al2O3/GaN MOSFETs. The positive interface charges were proposed originating...
In this work, a high performance AlGaN/GaN power diode featuring MIS-gated hybrid anode (MG-HAD) with ultralow forward turn-on voltage (VT) and low reverse leakage current was experimentally demonstrated. By accurately designing the recessing depth in the MIS-gate region, a record low VT of 0.2 V for GaN power diode was obtained in the MG-HAD with 4-nm recessed-barrier-thickness. Meanwhile, the device...
Capacitance-voltage (C-V) characteristics have been measured in this paper to calculate the depth profiles of GaN carrier concentration in four different structure GaN-based HEMTs, revealing the consequences of Al2O3 oxide layer and etching depth on two-dimensional electron gas (2DEG) sheet density. Combining the energy band diagrams with the theoretical calculation formula of 2DEG, we analyzed corresponding...
An analytical model for threshold voltage of the normally-off GaN-based fin-shaped field-effect transistor (FinFET) is obtained. Analytical expressions for the threshold voltage and its roll-off effect are presented. Some design insights can be obtained from the results. The explicit expression for threshold voltage makes the model suitable to be embedded in circuit simulation and design tools.
GaN-based vertical field effect transistors (VFETs) are very promising in various power switching applications owing to their high current density and small chip size. However, it is still challenging to obtain high breakdown voltage (BV) and low on-resistance (Ron) in the practical VFETs. Design and simulation of the device structures are necessary in shortening the device development progress. In...
Stable normally-off operation with high threshold voltage (Vth) is strongly desired in power switching applications. A p-GaN area under the barrier-recessed gate is employed to improve the Vth and off-state characteristics of the GaN-based HEMTs. TCAD-based device simulations are carried out to demonstrate and optimize the proposed structures. Finally, improved performances with Vth over 5V and breakdown...
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