Textured Magnesium Titanate as Gate Oxide for GaN-Based Metal-Oxide-Semiconductor Capacitor

Abstract

We demonstrate the first high‐permittivity ceramic oxide for use as the gate oxide of the GaN‐based metal‐oxide‐semiconductor (MOS) capacitor. An ilmenite magnesium titanate (MgTiO3) thin film prepared by sputtering was studied. When oxygen was introduced during sputtering, the preferred orientation changed from spinel Mg2TiO4 (111) to ilmenite MgTiO3 (003). The X‐ray diffractometry θ−2θ and φ‐scans were performed to identify the preferred films. Possible epitaxial relationships at the Mg2TiO4 (111)/GaN (001) and MgTiO3 (003)/GaN (001) interfaces were proposed. Finally, the electrical properties of the Al/MgTiO3 (003)/GaN (001)/Al MOS capacitor were presented.

Controlling the Electronic, Structural, and Optical Properties of Novel MgTiO3/LaNiO3 Nanostructured Films for Enhanced Optoelectronic Devices

“…These bands are probably formed from an overlap of the vibrational modes of both MTO (214 and 390 cm -1 ) and LNO (203 and 397 cm -1 ) materials. As can be observed by the deconvolution, the vibrational mode A g referring to the pure MTO is shifted to smaller Raman-active mode lengths (from 227 to 214 cm −1 ) in the multilayer film, indicating that the interaction with the LNO causes a short-range lattice ordering [19][20][21][22][23][24][25][26][27]. Figure 4 shows the FE-SEM micrographs of the surface microstructure and crosssection of the LNO/Si, MTO/Si, and MTO/LNO/Si thin films.…”

“…According to Chaban et al, the A 1g mode is a soft mode driving the structural distortion in the R c perovskites. The Raman-active mode located at 148 cm –1 can be described as pure La vibrations along the a - and b -axes of the structure in the hexagonal {001}-plane . Moreover, the Raman-active modes located at 397 and 443 cm –1 were caused by the vibrational modes of the oxygen cage …”

“…In this case, the MR measurements were employed to gain insights into the short-range structural order of these nanostructured films. Figure 3 According to group theory, the LNO phase with a rhombohedral structure belongs to the R c space group and has 27 optical modes, but only five are Raman-active modes (e.g., A 1g + 4E g ) [19,20]. We experimentally observed four Raman-active modes for the LNO thin film at approximately 148 (E g ), 203 (A 1g ), 397 (E g ), and 443(E g ) cm −1 , respectively, as can be seen in Figure 3(a).…”

Composite Mg2TiO4(111)/MgO (111) Gate Oxide on GaN (001)

“…13,14 In addition, the lattice mismatch between Mg 2 TiO 4 (or MgO) and GaN was small, as listed in Table I. MgO also has fcc oxygen atoms, and both the Mg and the O in MgO occupy the octahedral sites of each other.…”

“…The closepacked oxygen atoms in the (111) faces of Mg 2 TiO 4 and MgO can be grown epitaxially on GaN (001), by analogy with well-known GaN(001) on Si(111) or GaN (001) on sapphire (001). 13,14 In addition, the lattice mismatch between Mg 2 TiO 4 (or MgO) and GaN was small, as listed in Table I. Figure 1 plots the proposed atomic stacking sequence between Mg 2 TiO 4 (111)/GaN (001) and Mg 2 TiO 4 (111)/MgO (111)/GaN (001).…”