Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 27: Nitrides: Preparation and characterization II
HL 27.8: Vortrag
Mittwoch, 14. März 2018, 11:30–11:45, EW 203
X-ray diffraction studies of zincblende GaN — •Martin Frentrup1, Lok Yi Lee1, Suman-Lata Sahonta1, Menno J. Kappers1, Rachel A. Oliver1, Colin J. Humphreys1, and David J. Wallis1,2 — 1Department of Materials Science and Metallurgy, University of Cambridge, UK — 2Centre for High Frequency Engineering, University of Cardiff, UK
A possible approach in solving the green gap problem is the growth of III-nitrides in the cubic zincblende phase (zb) with its non-polar nature and reduced bandgap compared to the common wurtzite (wz) GaN phase. However, the relative metastability of the zb phase and low stacking-fault energy, lead to phase mixing and incorporation of planar defects. XRD texture maps of our GaN thin films on 3C-SiC/Si reveal that under optimised MOVPE growth conditions the zb phase can be stabilized as the dominant phase. In non-optimised thin films distorted hexagonal-like reflection patterns were observed originating from a low concentration of wz phase inclusions. Our results also indicate that depending on the template miscut, the growth of wz-like inclusions may occur preferentially along certain directions. Following growth optimisation the hexagonal patterns were very weak with intensities only slightly above the noise level. Reciprocal space maps revealed that these signals are caused by diffuse scattering from stacking faults, while reflections from the wz phase could not be observed.
The presence of dominant cubic phase was also confirmed by TEM measurements, showing a periodic ... AaBbCc ... stacking of the atomic layers typical for the cubic zb structure.