2005/03/21 by R. K. Kremer, M. Cardona, E. Schmitt +11 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Acoustic Wave Resonator Technologies #GaN-based semiconductor devices and materials #Thermal properties of materials #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.72.075209
12 pages, 5 Figures, submitted to PRB
arxiv created 2005/03/21 · openalex publication_date 2005/08/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Until recently, the heat capacity of GaN had only been measured for polycrystalline powder samples. Semiempirical as well as first-principles calculations have appeared within the past few years. We present in this article measurements of the heat capacity of hexagonal single crystals of GaN in the 20--1400\phantom\rule0.3em0exK temperature range. We find that our data deviate significantly from the literature values for polycrystalline materials. The dependence of the heat capacity on the isotopic mass has also been investigated recently for monatomic crystals such as diamond, silicon, and germanium. Multiatomic crystals are expected to exhibit a different dependence of these heat capacities on the masses of each of the isotopes present. These effects have not been investigated in the past to our knowledge. We also present first-principles calculations of the dependence of the heat capacities of GaN, as a canonical binary material, on each of the Ga and N masses. We show that they are indeed different, as expected from the fact that the Ga mass affects mainly the acoustic, that of N the optic phonons. It is hoped that these calculations will encourage experimental measurements of the dependence of the heat capacity on isotopic masses in binary and more complex semiconductors.