The new insight into gallium nitride (GaN) melting under pressure

TL;DR

This paper resolves longstanding questions about the phase diagram and melting temperature of gallium nitride under pressure, revealing a reversal melting point and potential fluid-fluid crossover at high pressures, which is crucial for GaN technology development.

Contribution

It introduces a novel method for determining GaN's melting temperature under high pressure and clarifies its phase diagram up to 9 GPa, including reversal melting behavior.

Findings

Determined GaN melting temperature up to 9 GPa.

Identified reversal melting behavior above 22 GPa.

Suggested fluid-fluid crossover at extreme pressures.

Abstract

Results solving the long standing puzzle regarding the phase diagram and the pressure evolution of the melting temperature Tm(P) of gallium nitride (GaN), the most promising semiconducting material for innovative modern electronic applications, are presented. The analysis is based on (i) studies of the decomposition curve in P-T plane up to challenging P equal 9 GPa, (ii) novel method enabling Tm(P) determination despite the earlier decomposition, and (iii) the pressure invariant parameterization of Tm(P) curve, showing the reversal melting for P greater-than 22 GPa. This is linked to a possible fluid-fluid crossover under extreme pressures and temperatures. The importance of results for the development of GaN based technologies is indicated.