Thermal conductivity of isotopically enriched⁷¹GaAs crystal

Abstract

A gallium arsenide bulk crystal highly enriched with gallium isotope 71 Ga to 99.40 at% has been grown using the seedless horizontal Bridgman method. The crystal has a total impurity concentration of about 2 × 10 17 atoms cm −3 and a high electrical resistivity ρ(300 K) ∼ 10 3 -10 8 cm. Thermal conductivity measurements have been made from 90 K to 300 K of the enriched 71 GaAs sample and three different nat GaAs samples with a natural isotope composition of gallium. The 71 GaAs has a higher value of thermal conductivity due to reduced isotope scattering of phonons: the observed isotope effect amounts to 5% at room temperature, increasing to 13% with a temperature decrease down to 100 K.

Ab initiothermal transport in compound semiconductors

“…All of the theoretical curves lie above the experimental data from Ref. 48 and agree somewhat better with the data from Ref. 47.…”

“…Figure 3 shows the calculated κ natural for GaAs with different nearest neighbor cut-off radii along with experimental data for κ natural (green triangles [47] and black triangles [48]) and κ L for isotopically purified GaAs (green circles [47] and black circles [48]). The calculated curves included 2 nd (green), 3 rd (solid black), 4 th (red), and 5 th (blue) nearest neighbors for the anharmonic IFCs.…”

“…Experimental data is shown for κ L of GaSb (black circles [56]), GaAs (green circles [47] and green triangles [48]), and GaP (red circles [51] and red triangles [52]). For GaN the lattice constant determined by energy minimization was increased ~1% to give better agreement with the experimental phonon dispersion as discussed in Ref.…”

“…The green dashed curve corresponds to κ natural without TI conditions enforced. Figure 3 Calculated κ natural vs. temperature for GaAs with experimental data for isotopically enriched GaAs (green circles [47] and black circles [48]) and for naturally occurring Ga concentrations (green triangles [47] and black triangles [48] AlSb is given by the dashed black curve. The acoustic-only contribution to κ natural for AlSb is given by the dotted black curve.…”

“…The solid curves give κ pure and the dashed curves give κ natural . Experimental data is shown for κ L of GaSb (black circles [56]), GaAs (green circles [47] and green triangles [48]), and GaP (red circles [51] and red triangles [52]). InP (black circles [59], squares [60], diamond [61], and triangle [62]), InAs (red circles [63], squares [64], diamond [65], and triangles [66]), and InSb (blue circles [56], squares [67], and triangles [68]).…”