Development of strain reduced GaN on Si (111) by substrate engineering

Abstract

We report on a novel scheme of substrate engineering to obtain high-quality GaN layers on Si substrates. Ion implantation of an AlN∕Si substrate is performed to create a defective layer that partially isolates the III-nitride layer and the Si substrate and helps to reduce the strain in the film. Raman spectroscopy shows a substantial decrease in in-plane strain in GaN films grown on nitrogen implanted substrates. This is confirmed by the enhancement of the E2 (TO) phonon frequency from 564 to 567cm−1 corresponding to 84% stress reduction and substantial decrease in crack density for a 2-μm-thick GaN film. GaN films grown on implanted AlN∕Si substrate have better optical properties and smoother surface morphology as compared to nonimplanted AlN∕Si substrate.

Dislocation reduction in GaN grown on Si(111) using a strain-driven 3D GaN interlayer

“…Extensive studies on dislocation reduction for GaN layers grown on silicon already exist [3][4][5][6] but in order to achieve high dislocation reduction ratios a combination of different dislocation reduction techniques, which can be combined with a strain management layer such as graded AlGaN layers, may be required. In this paper we demonstrate the formation of a 3D GaN island layer for dislocation reduction without the need for an ex situ or in situ deposition of a SiO 2 or SiN x mask (in contrast to [7,8]).…”

Epitaxial Lateral Overgrowth of GaN on Si (111) Substrates Using High‐Dose, N+ Ion Implantation

“…Ion implantation has been introduced to a Si substrate for GaN growth by several groups. [8,9] However, the ion-implanted Si was intended for use as a buffer layer for the relaxation of the film stress; medium doses of $10 16 cm À2 were used. Figure 1 shows the schematic diagram of our ELO process for low-defect GaN film.…”

Single crystalline GaN grown on porous Si(111) by MOVPE

“…Stress engineering has to be applied to prevent cracking and substrate engineering could be an effective method to reduce the stress in the epitaxial GaN layers. Crack-free GaN has been grown on patterned silicon substrates [4], N + ion implanted silicon substrates [5] and SOI substrates [6]. A thin single crystalline silicon layer is used as a compliant template, which is separated from the bulk silicon substrate by a defective layer in the case of the N + ion implanted silicon substrates or by an amorphous oxide layer when SOI substrates are used.…”