Low Pressure Chemical Vapor Deposition Growth of Wide Bandgap Semiconductor In₂O₃ Films

Abstract

Wide-bandgap semiconductor indium sesquioxide (In2O3) thin films were grown on yttria-stabilized-zirconia (YSZ) substrates with (100), (110), and (111) orientations using a previously unexplored growth method: low pressure chemical vapor deposition. High purity metallic indium (In) and oxygen (O2) were used as precursors, and argon (Ar) was used as the carrier gas. The growth condition was optimized to balance the precursor vapor pressure and the suppression of the gas phase reaction to facilitate the growth of high crystalline quality In2O3 films. The crystal structures of the as-grown films were determined to be body centered cubic bixbyite. By tuning the O2 flow rate, In2O3 epitaxial growth rates of 21 μm/h, 11 μm/h, and 9.2 μm/h were obtained for films grown on YSZ (100), (110), and (111) substrates, respectively. Representative surface roughness values determined by atomic force microscopy ranges between 0.73 and 10.5 nm. Room temperature electron Hall mobility of 139 cm2/V·s, 77 cm2/V·s, and 97 cm2/V·s for (100), (110), and (111) oriented In2O3 films respectively were obtained with electron concentrations of (∼1.0–1.3) × 1018 cm–3. Secondary ion mass spectroscopy suggests H as a possible contributor to the observed free carrier concentrations in the as-grown films. A room temperature photoluminescence peak was observed at ∼2.16 eV, which is related to the transition involving deep-level defects. Optical bandgap was determined to be ∼3.35–3.41 eV via photoluminescence excitation spectroscopy.

Band Alignment and Enhanced Interfacial Conductivity Manipulated by Polarization in a Surfactant-Mediated Grown κ-Ga2O3/In2O3 Heterostructure

“…18,19 With the In 2 O 3 buffer layer, the subsequent growth of single crystalline Sn-doped Ga 2 O 3 was stabilized in the pure κ-phase, and the only observed diffraction peak at 38.80°corresponds to the κ-Ga 2 O 3 (004) plane. 11,20 As a result, the out-of-plane relationship is κ- The diffraction pattern for the κ-Ga 2 O 3 (102) plane exhibits a six-fold symmetry, which is resulted from the (001)-oriented κ-Ga 2 O 3 orthorhombic rotational domains formed on (111)-oriented cubic substrates with a relative azimuth of 120°, consistent with reported κ-Ga 2 O 3 on NiO 21 and ITO. 22 Consequently, the in-plane epitaxial relationship between the epilayer and the substrate is…”

“…For the Ga 2 O 3 layer directly grown on YSZ (111), no diffraction peaks corresponding to Ga 2 O 3 were observed, indicative of its amorphous state. In comparison, the pure-phase cubic-structured In 2 O 3 epitaxial layers were grown on the YSZ (111) substrate owing to its thermodynamically most stable termination and the lowest energy cleavage plane, as evidenced by the dominant diffraction peak at 30.52°. , With the In 2 O 3 buffer layer, the subsequent growth of single crystalline Sn-doped Ga 2 O 3 was stabilized in the pure κ-phase, and the only observed diffraction peak at 38.80° corresponds to the κ-Ga 2 O 3 (004) plane. , As a result, the out-of-plane relationship is κ-Ga 2 O 3 [004]//In 2 O 3 [222]//YSZ [111]. Figure b shows the XRD Φ-scan patterns of cubic-In 2 O 3 (044) and orthorhombic κ-Ga 2 O 3 (102).…”

Optical phonon modes, static and high-frequency dielectric constants, and effective electron mass parameter in cubic In2O3

“…Most existing works study thin film samples and as a result, most of the applications are designed around thin film samples as well. 22 Bierwagen and Speck reported high quality thin films grown by plasmaassisted molecular beam epitaxy (PAMBE); 4,23 Yang et al reported similarly high quality thin films grown by metal organic vapor phase epitaxy; 24 and Karim, Feng, and Zhao reported high quality thin films grown by low pressure chemical vapor deposition, 25 for example. Recently, Galazka et al developed a high quality single crystal bulk growth method, and thereby provided substrates with large surface areas for epitaxy.…”

Optical phonon modes, static and high frequency dielectric constants, and effective electron mass parameter in cubic In$_2$O$_3$

“…Most existing works study thin film samples and as a result, most of the applications are designed around thin film samples as well. 22 Bierwagen and Speck reported high quality thin films grown by plasmaassisted molecular beam epitaxy (PAMBE); 4,23 Yang et al reported similarly high quality thin films grown by metal organic vapor phase epitaxy; 24 and Karim, Feng, and Zhao reported high quality thin films grown by low pressure chemical vapor deposition, 25 for example. Recently, Galazka et al developed a high quality single crystal bulk growth method, and thereby provided substrates with large surface areas for epitaxy.…”