Stress reduction in epitaxial GaN films on Si using cubic SiC as intermediate layers

Abstract

Stress in the epitaxial films of GaN on Si is reduced by using SiC as intermediate layers. The crystalline films of cubic SiC (0–1μm), thin AlN (50nm), and GaN (1–3μm) were prepared on 3in. (1 1 1) Si substrates—stacked in the order of GaN∕AlN∕SiC∕Si—by metalorganic vapor-phase epitaxy. It is revealed by Raman spectroscopy that the tensile stress in GaN is reduced to half (reduction of about 300MPa) for GaN on Si with SiC intermediate layers compared with GaN on Si without SiC intermediate layers. Because of stress reduction, crack-free GaN on Si with a thickness of 2μm was obtained by using SiC intermediate layers. Cracking was minimized even on thicker GaN on Si (3μm thick) with SiC intermediate layers. The SiC intermediate layers are promising for the realization of nitride based electronic devices on Si.

MOVPE of AlN-free hexagonal GaN/cubic SiC/Si heterostructures for vertical devices

“…An intermediate layer, also called as a buffer layer, that reduces the stress in the heteroepitaxy of GaN on Si is needed. In the previous paper, we have reported the stress reduction in GaN on Si using cubic SiC (3C-SiC) intermediate layers [9][10][11]. The (111)-oriented 3C-SiC has a lattice structure close to that of GaN (0 0 0 1)-the basal plane of hexagonal GaN.…”

“…The lattice mismatch between GaN (0 0 0 1) and 3C-SiC (111) is 3%, which is much smaller than that between GaN and Si (17%). Stress reduction is considered by employing 3C-SiC as the intermediate layers between GaN and Si [9][10][11]. Our previous works and the conventional growth of GaN on SiC by metalorganic vapor phase epitaxy (MOVPE) used AlN or AlGaN buffer layers (AlN buffers) to obtain GaN with a smooth surface [9][10][11][12][13][14].…”

Effect of hydrogen flow on growth of 3C-SiC heteroepitaxial layers on Si(111) substrates

“…Due to the difficulties in growing bulk 3C-SiC crystals, heteroepitaxial growth of 3C-SiC films on silicon (Si) substrate has been developed [4]. As the only polytype which can be grown on the Si substrate, 3C-SiC has a remarkable advantage in the low-cost fabrication of large diameter wafers and power devices [5][6][7]. However, device applications using 3C-SiC grown on Si substrate have been lagged, owing to the difficulty in realizing high throughput of high quality material which is restricted by the large lattice mismatch (about 20%) and significant difference in thermal expansion coefficient (about 8%) between 3C-SiC epilayer and the silicon substrate [8].…”

Realization of AlGaN/GaN HEMTs on 3C‐SiC/Si(111) substrates

“…On the other hand, (111) oriented cubic SiC can be employed as an intermediate layer for the growth of hexagonal phase GaN on Si. The suppression of crack generation in GaN grown on 3C-SiC/Si [10,11] as well as an enhancement of GaN crystal quality as compared with similar structures grown on Si [12,13] 2 Experimental Good quality 3C-SiC thick films are obtained by chemical vapor deposition (CVD). In this work, up to 2.2 µm 3C-SiC films were grown on 2 in.…”