Cyclotron resonance and quantum Hall effect studies of the two-dimensional electron gas confined at the GaN/AlGaN interface

Abstract

We report on high magnetic fields (up to 40 T) cyclotron resonance, quantum Hall effect and Shubnikov-de-Hass measurements in high frequency transistors based on Si-doped GaN–AlGaN heterojunctions. A simple way of precise modelling of the cyclotron absorption in these heterojunctions is presented. We clearly establish two-dimensional electrons to be the dominant conducting carriers and determine precisely their in-plane effective mass to be 0.230±0.005 of the free electron effective mass. The increase of the effective mass with an increase of two-dimensional carrier density is observed and explained by the nonparabolicity effect.

Quantum confinement effect on the effective mass in two-dimensional electron gas of AlGaN/GaN heterostructures

“…5. The points with the reference marks [15][16][17][21][22][23]28,29 correspond to experimental data, taken from the literature and the points with the letter marks A, B, and C represent our experimental data. The solid line is the fit of the 2DEG effective mass dependence on the probability of wave-function penetration into the barrier of the studied AlGaN/GaN heterostructures.…”

“…We determined the probabilities of the 2DEG wavefunction penetration into the barrier by self-consistent calculation for our AlGaN/GaN samples and for HEMT GaNbased heterostructures reported in the literature [15][16][17][21][22][23]28,29 containing all necessary information for the detailed simulation.…”

“…On leave from Institute of Semiconductor Physics, NASU, 03028 Kiev, Ukraine. JOURNAL OF APPLIED PHYSICS 105, 073703 ͑2009͒ resonance [14][15][16] and magnetotransport [17][18][19] results͒ that the inplane effective mass can exceed the bulk values considerably due to the increasing effect of conduction band nonparabolicity at higher Fermi energy. At the same time, even taking into account this effect, a large scatter of the data is not well understood and uncertainty of the effective mass in 2DEG with different carrier density and spatial confinement is large.…”

“…Even in high-quality AlGaN/GaN heterostructures, the in-plane effective mass of 2D electrons measured by various direct and indirect techniques has shown effective mass enhancement and a large scatter of the data [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] ͑Fig. 1͒.…”

Terahertz cyclotron resonance spectroscopy of an AlGaN/GaN heterostructure using a high-field pulsed magnet and an asynchronous optical sampling technique

“…6 However, the precise measurement of the larger electron effective mass in GaN requires large magnetic fields which are typically only available at national-scale facilities. 7,8 Recently, compact pulsed magnets have been developed, which can provide the high magnetic fields (up to 30 T) that were previously only accessible at national-scale facilities on a table-top in a laboratory environment. 9 There have also been several reports of cyclotron resonance spectrometers being developed that combine pulsed magnetic fields with broadband laser-based terahertz radiation sources.…”