Spontaneous emission of color centers at 4eV in hexagonal boron nitride under hydrostatic pressure

TL;DR

This study investigates how hydrostatic pressure affects the UV light emission of color centers in hexagonal boron nitride, revealing unique pressure-dependent behaviors that deepen understanding of these deep trap states.

Contribution

It provides new insights into the pressure-dependent emission properties of UV-emitting color centers in hBN, highlighting levels that behave differently under pressure.

Findings

Emission energy decreases with pressure but less than the bandgap.

Discovery of levels with different pressure responses, including decreasing emission wavelength.

Reveals complex behavior of deep traps in hBN under pressure.

Abstract

The light emission properties of color centers emitting in 3.3-4 eV region are investigated for hydrostatic pressures ranging up to 5GPa at liquid helium temperature. The light emission energy decreases with pressure less sensitively than the bandgap. This behavior at variance from the shift of the bandgap is typical of deep traps. Interestingly, hydrostatic pressure reveals the existence of levels that vary differently under pressure (smaller increase of the emission wavelength compared to the rest of the levels in this energy region or even decrease of it) with pressure. This discovery enriches the physics of the color centers operating in the UV in hBN.