Facet-dependent electrical conductivity properties of GaN wafers

Abstract

An intrinsic {0001} GaN wafer cut to expose {1010} side faces allows examination of its conductivity properties with respect to the crystal faces. Interestingly, the {1010} face shows a 10-fold...

Surface-dependent band structure variations and bond deviations of GaN

“…16 Although smaller band gaps obtained for certain numbers of (10% 10) planes would suggest a better electrical conductivity for the {10% 10} surface compared to the {0001} face, experimentally the {0001} face is much more conductive. 32 Such inconsistency was also observed for the somewhat conductive (100) and insulative (110) planes of Cu 2 O with a consistent band gap of 1.787 eV for the (100) planes. 16 Nevertheless, the DFT calculations suggest that the (0001) and (10% 10) planes should have different conductivity properties.…”

“…[27][28][29][30][31] Recently, an intrinsic {0001} GaN wafer cut to expose {10% 10} side faces has been used for facet-specific electrical conductivity and photoluminescence measurements, showing that the {0001} face is much more conductive than the {10% 10} face. 32 However, the {10% 10} face gives much stronger photoluminescence than the {0001} face does. To explain the observation of the electrical facet effect in GaN wafers, DFT calculations have been performed on GaN (0001), (10% 10), and (10% 11) planes to see the plane layer-dependent variation in the band structure and band gap, as well as deviations in bond length and bond direction for the (10% 10) and (10% 11) planes.…”

Probing crystallographic orientation-specific carrier lifetimes in epitaxial Ge/AlAs and InGaAs/InP heterostructures

“…Carrier lifetimes from lattice-matched Ge/AlAs heterostructures with three different surface orientations were determined by a non-contact m-PCD method. As discussed above, the carrier lifetime has a strong orientation dependence on elementary (Si, Ge) and binary (GaAs, GaN) semiconductors, 23,26,28,37 as well as a few oxide materials. 31,32 Over the decades, different measurement techniques, such as temperature-dependent photoluminescence, microwave reflection and transmission probing, and non-contact PCD, have been developed [42][43][44][45][46][47][48][49][50][51][52][53][54] for the determination of the carrier lifetime.…”

Origin and manifestation of semiconductor facet effects

“…Similar current‐rectifying responses have been observed in Ge, GaAs, and GaN wafers. [ 9–11 ] For example, the GaAs {111} face is much more conductive than its {100} and {110} faces. Current rectification is therefore observed for the GaAs {110}/{111} facet combination.…”

“…[ 7 ] Moreover, intrinsic Si, Ge, GaAs, and GaN wafers also exhibit clear facet dependence in their electrical conductivity properties. [ 8–11 ] The fact electrical facet effects occur on the same particle or wafer suggests that charge transport strongly depends on the contacting surface, as the crystal bulk should be the same. This naturally implies that different faces of the same material are more different than simply the surface atomic arrangement, as electron density cannot be zero, and the surface difference should extend to some depths beyond the first lattice plane.…”