Influence of substrate nitridation temperature on epitaxial alignment of GaN nanowires to Si(111) substrate

Abstract

An arrangement of self-assembled GaN nanowires (NWs) grown by plasma-assisted molecular beam epitaxy on a Si(111) substrate is studied as a function of the temperature at which the substrate is nitridized before GaN growth. We show that the NWs grow with the c-axis perpendicular to the substrate surface independently of nitridation temperature with only a slight improvement in tilt coherency for high nitridation temperatures. A much larger influence of the substrate nitridation process on the in-plane arrangement of NWs is found. For high (850 °C) and medium (450 °C) nitridation temperatures angular twist distributions are relatively narrow and NWs are epitaxially aligned to the substrate in the same way as commonly observed in GaN on Si(111) planar layers with an AlN buffer. However, if the substrate is nitridized at low temperature (~150 °C) the epitaxial relationship with the substrate is lost and an almost random in-plane orientation of GaN NWs is observed. These results are correlated with a microstructure of silicon nitride film created on the substrate as the result of the nitridation procedure.

Liquid-target reactive magnetron sputter epitaxy of High quality GaN(0001̄) nanorods on Si(111)

“…8(a) GaN growth. This is in agreement with findings for plasma-assisted MBE growth of similar GaN nanorods grown on Si(111) at high temperature, where an oriented crystalline $2 nm-thick nitrided layer, formed prior to growth, was shown to induce the azimuthal orientation of the nanorods [31,33,34]. It was furthermore shown that an amorphous nitrided layer of equal thicknes did not induce any in-plane orientation of the subsequently grown GaN nanorods.…”

Quantified hole concentration in AlGaN nanowires for high-performance ultraviolet emitters

“…3(d), the diffracted X-ray beam intensity distributions are located in the center of the pole figure, which indicates that the c-axis of most of the AlGaN nanowires is perpendicular to the substrate and agrees with the θ-2θ scan result. 64,65 Moreover, a distribution of the tilt angles of the AlGaN nanowires with the [0002] axis is also expected because of the rough substrate surface. Fig.…”

Elastic versus Plastic Strain Relaxation in Coalesced GaN Nanowires: An X-Ray Diffraction Study

“…Prior to nanowire nucleation, the Si substrate is nitridated by the N plasma inducing the formation of an amorphous SiN x interlayer. Nevertheless, the in-plane orientation of the nanowires clearly follows that of the Si(111) substrate with a deviation (twist) of about 3 • [20,29]. To simplify the calculations below and to preserve a symmetric shape of the nanowires, we assume that relaxation at the interface proceeds in the same way as at the joints.…”