In this paper, the feasibility of an indium−gallium oxide (In 2(1-x) Ga 2x O y ) film through combinatorial atomic layer deposition (ALD) as an alternative channel material for back-endof-line (BEOL) compatible transistor applications is studied. The microstructure of random polycrystalline In 2 O y with a bixbyite structure was converted to the amorphous phase of In 2(1−x) Ga 2x O y film under thermal annealing at 400 °C when the fraction of Ga is ≥29 at. %. In contrast, the enhancement in the orientation of the (222) face and subsequent grain size was observed for the In 1.60 Ga 0.40 O y film with the intermediate Ga fraction of 20 at. %. The suitability as a channel layer was tested on the 10-nm-thick HfO 2 gate oxide where the natural length was designed to meet the requirement of short channel devices with a smaller gate length (<100 nm). The In 1.60 Ga 0.40 O y thin-film transistors (TFTs) exhibited the high field-effect mobility (μ FE ) of 71.27 ± 0.98 cm 2 /(V s), low subthreshold gate swing (SS) of 74.4 mV/decade, threshold voltage (V TH ) of −0.3 V, and I ON/OFF ratio of >10 8 , which would be applicable to the logic devices such as peripheral circuit of heterogeneous DRAM. The in-depth origin for this promising performance was discussed in detail, based on physical, optical, and chemical analysis.

In this study, plasma-enhanced atomic layer deposited indium oxide (InOx) films were analyzed using a new [dimethylbutylamino]trimethylindium (DATI) liquid precursor and Ar/O2 plasma. The growth property using the DATI precursor, such as growth per cycle, is relatively higher (≥1.0 Å/cycle) than other precursors even in low deposition temperatures (100–250 °C). In addition, impurities (C and N) in the thin films were below the XPS detection limit. Because the number of oxygen vacancies that generate carriers in the InOx thin films increased with the deposition temperature, the carrier concentration (2.7 × 1018–1.4 × 1019 cm−3) and Hall mobility (0.3–1.1 cm2/V s) of the InOx thin film were increased. InOx channel based staggered bottom gate structure thin film transistors (TFTs) were fabricated, and their switching performance were studied. Because the InOx films were deposited with high purity, the electrical properties of TFTs show superior switching performance in terms of saturation mobility (17.5 cm2/V s) and Ion/Ioff ratio (2.9 × 109). Consequently, InOx films deposited with DATI have the potential to be widely used in indium oxide semiconductors, especially backplane TFTs.

A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. We aimed to systematically investigate the dependence of SiC epilayer quality and growth rate during the sublimation growth using the CST method on various process parameters such as the growth temperature and working pressure. The etched surface of a SiC epitaxial layer grown with low growth rate (30 μm/h) exhibited a low etch pit density (EPD) of ~2000 /cm2 and a low micropipe density (MPD) of 2 /cm2. The etched surface of a SiC epitaxial layer grown with a high growth rate (above 100 μm/h) contained a high EPD of ~3500 /cm2 and a high MPD of ~500 /cm2, which indicates that high growth rate aids the formation of dislocations and micropipes in the epitaxial layer.

A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. In this study, we aimed to systematically investigate surface morphologies and electrical properties of SiC epitaxial layers grown with varying a SiC/Al ratio in a SiC source powder during the sublimation growth using the CST method. It was confirmed that the acceptor concentration of epitaxial layer was continuously decreased with increasing the SiC/Al ratio. The blue light emission was successfully observed on a PN diode structure fabricated with the p-type SiC epitaxial layer. Furthermore, 4H-SiC MESFETs having a micron-gate length were fabricated using a lithography process and their current-voltage performances were characterized.

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