Spectroscopic Ellipsometry and Correlated Studies of AlGaN-GaN HEMTs Prepared by MOCVD.

ABSTRACT: A series of AlGaN/GaN high-electron-mobility transistor (HEMT) structures, with an AlN thin buffer, GaN thick layer and Al_0.25Ga_0.75N layer (13-104 nm thick), is prepared by metal-organic chemical vapor deposition and investigated via multiple techniques. Spectroscopic ellipsometry (SE) and temperature-dependent measurements and penetrative analyses have achieved significant understanding of these HEMT structures. Bandgaps of AlGaN and GaN are acquired via SE-deduced relationships of refraction index n and extinguish coefficient k vs. wavelength λ in a simple but straightforward way. The optical constants of n and k, and the energy gap E_g of AlGaN layers, are found slightly altered with the variation in AlGaN layer thickness. The Urbach energy E_U

SUBMITTER: Yang Y 

PROVIDER: S-EPMC11820650 | biostudies-literature | 2025 Jan

REPOSITORIES: biostudies-literature