A simple method of extracting the polarization charge density in the AlGaN/GaN heterostructure from current-voltage and capacitance-voltage characteristics

In this study rectangular AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with 22-nm and 12-nm AlGaN barrier layers are fabricated, respectively. Using the measured capacitance–voltage and current–voltage characteristics of the prepared devices with different Schottky areas, it is found that after processing the device, the polarization Coulomb field (PCF) scattering is induced and has an important influence on the two-dimensional electron gas electron mobility. Moreover, the influence of PCF scattering on the electron mobility is enhanced by reducing the AlGaN barrier thickness. This leads to the quite different variation of the electron mobility with gate bias when compared with the AlGaN barrier thickness. This mainly happens because the thinner AlGaN barrier layer suffers from a much stronger electrical field when applying a gate bias, which gives rise to a stronger converse piezoelectric effect.

Section: Calculation and Analysesmentioning

confidence: 99%

Influence of the AlGaN barrier thickness on polarization Coulomb field scattering in an AlGaN/AlN/GaN heterostructure field-effect transistor

Li¹,

Feng²,

Gu³

et al. 2015

“…[1] Low frequency noise (LFN) in HEMT is important since it becomes an important limitation of the device performances. These mechanisms originate either from trapping-detrapping processes in surface states and deep traps associated with material quality induced by piezoelectric polarization effects [2,3] or from permanent degradation induced by hot carrier interaction with trap sites occurring in the gatedrain region. [4] Although in as early as 1998, Balandin et al [5] measured the GaN-based HEMTs 1/ f noise.…”

Section: Introductionmentioning

confidence: 99%

A unified drain current 1/fnoise model for GaN-based high electron mobility transistors

Liu¹,

Zhang²,

Ma³

et al. 2014

In this work, we present a theoretical and experimental study on the drain current 1/ f noise in the AlGaN/GaN high electron mobility transistor (HEMT). Based on both mobility fluctuation and carrier number fluctuation in a twodimensional electron gas (2DEG) channel of AlGaN/GaN HEMT, a unified drain current 1/ f noise model containing a piezoelectric polarization effect and hot carrier effect is built. The drain current 1/ f noise induced by the piezoelectric polarization effect is distinguished from that induced by the hot carrier effect through experiments and simulations. The simulation results are in good agreement with the experimental results. Experiments show that after hot carrier injection, the drain current 1/ f noise increases four orders of magnitude and the electrical parameter degradation ∆g m /g m reaches 54.9%. The drain current 1/ f noise degradation induced by the piezoelectric effect reaches one order of magnitude; the electrical parameter degradation ∆g m /g m is 11.8%. This indicates that drain current 1/ f noise of the GaN-based HEMT device is sensitive to the hot carrier effect and piezoelectric effect. This study provides a useful reliability characterization tool for the AlGaN/GaN HEMTs.

“…[14] Compared with a GaAs material system, a GaN material system has a larger LO phonon energy (∼ 90 meV). Its alloys with aluminum nitride and related quantum wells have attracted significant attention in recent years, resulting in many successful advances [15][16][17] based on this material system. Previous attempts to grow nonpolar GaN by vapor phase and molecular beam epitaxy yielded rough and faceted surfaces that were unsuitable for use in practical devices.…”

Section: Introductionmentioning

confidence: 99%

An optically pumped GaN/AlGaN quantum well intersubband terahertz laser

Fu¹,

Hao²,

Yang³

et al. 2013

We propose an optically pumped nonpolar GaN/AlGaN quantum well (QW) active region design for terahertz (THz) lasing in the wavelength range of 30 µm ∼ 40 µm and operating at room temperature. The fast longitudinal optical (LO) phonon scattering in GaN/AlGaN QWs is used to depopulate the lower laser state, and more importantly, the large LO phonon energy is utilized to reduce the thermal population of the lasing states at high temperatures. The influences of temperature and pump intensity on gain and electron densities are investigated. Based on our simulations, we predict that with a sufficiently high pump intensity, a room temperature operated THz laser using a nonpolar GaN/AlGaN structure is realizable.