Thermal Expansion Of GaN And Ain

Abstract

The temperature dependence of the thermal expansion and the bulk modulus are critical for predicting the residual stress distribution in epitaxial films and provides information relevant for interatomic potentials and equations of state. The thermal expansions of aluminum nitride (AIN) and gallium nitride (GaN) are calculated with two models that employ the limited elastic and lattice parameter data. These semiempirical models allow prediction of the thermal expansions to higher temperatures. Calculated results are compared with experimental data.

Structural and optical properties of Si-doped GaN

“…On the other hand, Lee et al 9 discuss a silicon-doping induced defect formation during the cool-down process as a possible origin of the stress relaxation. Results of other authors 6 indicate that the strain relaxation due to Si incorporation is not significant up to Si concentrations of 2ϫ10 17 cm Ϫ3 . Concerning the optical properties, a shift of the optical band gap E g towards lower energies with increasing silicon doping has often been observed, which was attributed to strain relaxation.…”

“…The difference of the thermal expansion coefficients ͑TEC͒ of the substrate and the epitaxial layer can account for the compressive stress found for the undoped sample. 17,18 This leads to the conclusion that the deposited layers were fully relaxed or only slightly stressed during the growth. The incorporation of Si into the layer not only leads to strain relaxation, as generally considered, but also induces tensile strain in the layer.…”

Temperature dependence of the E2h phonon mode of wurtzite GaN/AlN quantum dots

“…27,28 Due to the fact that the GaN and AlN contents of the QD sample are very different, the dependence of this "thermal strain" with temperature will be analyzed separately for both materials in the following sections.…”

High Al-Content AlInGaN Devices for Next Generation Electronic and Optoelectronic Applications

“…Additionally, it is apparent from SEM, XTEM, and AFM images that when deposition was continued past the critical thickness the AlGaN film partially overgrew the cracks, giving the false impression that the cracks did not propagate to the surface. Coherent epitaxy aluminum concentration determined from ex situ XRD and the approximate Al 0.17 Ga 0.83 N lattice parameter was calculated using a weighted average of the lattice constants of AlN and GaN at growth temperature [12]. The calculated coherency strain accounts for the initial stress up to the onset of stress relaxation using XRD.…”

“…Bright-field XTEM image of dislocations in Al 0.37 Ga 0.63 N/GaN, using twobeam diffraction conditions with g = (11)(12)(13)(14)(15)(16)(17)(18)(19)(20); specimen tilted 30°a bout [11][12][13][14][15][16][17][18][19][20] axis to broaden the projected image of the interface. 12.…”