Influence of the trench depths of grooved GaN templates on the characteristics of overgrown AlGaN films

In this study, the properties of Al_0.18Ga_0.82N films grown on stripe-grooved GaN templates with different trench depths have been investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), double crystal X-ray diffractometer (DCXRD), and photoluminescence (PL) measurement. Based upon the results of FESEM observations, a crack-free Al_0.18Ga_0.82N surface has been achieved using a GaN template with 1-μm-deep trenches. Moreover, from the observations of TEM, the density of threading dislocations in Al_0.18Ga_0.82N film was found to reduce during the lateral growth on the trench regions. DCXRD and PL both measurements were carried out to determine the quality of the Al_0.18Ga_0.82N films. The full-width at half-maxima of double crystal X-ray rocking curve and PL spectrum are the smallest, respectively, for the Al_0.18Ga_0.82N film grown on grooved GaN template having 1 μm-deep trenches. It is believed that the use of the grooved GaN templates effectively improves the quality of the overgrown Al_0.18Ga_0.82N films.

Source:Journal of Crystal Growth

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