Direct band gap carbon superlattices with efficient optical transition

TL;DR

This paper introduces pure carbon superlattices with direct wide band gaps and excellent optical properties, promising for deep ultraviolet light emission, and demonstrates their thermal stability and potential synthesis methods.

Contribution

It reports the design of novel pure carbon superlattices with direct band gaps and high optical efficiency, a significant advancement over traditional diamond structures.

Findings

Band gaps of 5.6-5.9 eV corresponding to 210-221 nm wavelengths

Superlattices exhibit optical transition dipole moments comparable to GaN

Thermally stable at temperatures up to 2000 K

Abstract

We report pure carbon-based superlattices that exhibit direct band gaps and excellent optical absorption and emission properties at the threshold energy. The structures are nearly identical to that of cubic diamond except that defective layers characterized by five- and seven-membered rings are intercalated in the diamond lattice. The direct band gaps lie in the range of 5.6~5.9 eV, corresponding to wavelengths of 210~221 nm. The dipole matrix elements of direct optical transition are comparable to that of GaN, suggesting that the superlattices are promising materials as an efficient deep ultraviolet light emitter. Molecular dynamics simulations show that the superlattices are thermally stable even at a high temperature of 2000 K. We provide a possible route to the synthesis of superlattices through wafer bonding of diamond (100) surfaces.