Bandgap narrowing and Mott transition in Si-doped Al0.7Ga0.3N
Abstract
Deep ultraviolet light-emitting diodes (LEDs) composed of III-Nitride semiconductors need layers of heavy doping (>1 × 1019 cm−3) to overcome large dopant activation energies and maintain high electrical conductivity. This work reports that at doping densities of [Si] ∼1.5 × 1019/cm3 for n-Al0.7Ga0.3N, Burstein-Moss and bandgap renormalization effects result in a net reduction of the bandgap of ∼70 meV. At these doping levels, a transition to a metallic conductivity state is observed, with a vanishing of the effective dopant activation energy. The sheet and contact resistivities of Rsh,n = 0.045 Ω cm and ρc,n = 1.13 × 10−6 Ω cm2 are achieved, with uniform conductivity in the vertical direction. The results show that when heavily doped n-AlGaN cladding regions are used for high efficiency deep-UV LEDs or lasers, the accompanying bandgap narrowing reduces the window of optical transparency at the lowest wavelengths that can take advantage of high conductivity.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 18, 2019
- Source ID
- 10.1063/1.5086052
Entities
People
- Alexander Chaney
- Debdeep Jena
- Huili Grace Xing
- Kazuki Nomoto
- S. M. Islam
- Shyam Bharadwaj
- Vladimir Protasenko
Organizations
- Air Force Office of Scientific Research
- Cornell University
- National Science Foundation