Band diagram

Quantum mechanics

Fermi level

Voltage

Surface states

Metallurgy

Materials science

Fermi gas

High-electron-mobility transistor

Mole fraction

Band gap

Surface (topology)

Quantum well

Physical chemistry

Laser

Transistor

Physics

Mathematics

Optics

Doping

Condensed matter physics

Geometry

Heterojunction

Chemistry

Electron

Shallow donor

Aluminium

Optoelectronics

Nanoscale Research Letters

The presence of surface traps is an important phenomenon in AlGaN/GaN HEMT. The electrical and physical properties of these surface traps have been analyzed through the study of 2DEG electron concentration along with the variation of aluminum percentage in the barrier layer of HEMT. This analysis shows that from deep to shallow donors, the percentage change in electron density in 2DEG gets saturated (near 8%) with change in aluminum concentration. The depth of the quantum potential well below the Fermi level is also analyzed and is found to get saturated (near 2%) with aluminum percentage when surface donor states energy changes to deep from shallow. The physics behind this collective effect is also analyzed through band diagram too. The effect of surface donor traps on the surface potential also has been discussed in detail. These surface states are modeled as donor states. Deep donor (EC - ED = 1.4 eV) to shallow donor (EC - ED = 0.2 eV) surface traps are thoroughly studied for the donor concentration of 1011 to 1016 cm-2. This study involves an aluminum concentration variation from 5 to 50%. This paper for the first time presents the comprehensive TCAD study of surface donor and analysis of electron concentration in the channel and 2DEG formation at AlGaN-GaN interface.

Impact of Surface States and Aluminum Mole Fraction on Surface Potential and 2DEG in AlGaN/GaN HEMTs