Fabrication of high-electron-mobility ZnO epilayers by chemical vapor deposition using catalytically produced excited water

Inference on the Production Mechanism of ZnO Thin Films from Activated Water and Dimethylzinc Molecules

“…In addition, no changes were observed when a glass substrate was placed 22 mm downstream from the nozzle exit. By comparing the experimental spectrum with a simulated one, the rotational temperature of H 2 O from the nozzle was determined to be 250 K. This is much lower than the temperature before expansion, 1700 K. 1) The absence of the ð1; 1; 0Þ-ð0; 1; 0Þ hot band around 3630 cm À1 suggests that the production of vibrationally excited H 2 O is minor. The procedure used to simulate the CARS spectrum was similar to those employed by other investigators [15][16][17][18] as well as by ourselves.…”

“…Nishiyama et al have estimated the catalyst temperature to be 1700 K. 1) The gas temperature before expansion must be similar. In a hydrodynamic flow, the ratio of the gas temperature after expansion to that before expansion, T/T 0 , is given by 31) .…”

“…Recently, Nishiyama et al have shown that high-quality ZnO epilayers can be fabricated from catalytically produced activated water vapor and dimethylzinc molecules. 1) They produced a beam of activated water vapor in a reaction of H 2 and O 2 on a Pt-dispersed ZrO 2 catalyst. The electron mobility in the ZnO films fabricated was 140-170 cm 2 V À1 s À1 , while the residual electron concentration was ð2{6Þ Â 10 17 cm À3 .…”

In Situ Interferometry of MOCVD-Grown ZnO for Nucleation-Layer-Based Optimization and Nanostructure Formation Monitoring

“…These results are in good agreement with previously reported results. [39][40][41] The results for optimized NL thickness based on in situ interferometry are summarized in Table I. Based on the measured reflectance thickness oscillations and their degradation during high-temperature growth, it was found that the nucleation layer thickness necessary for optimum HT growth of ZnO at 430°C is 32 nm to 40 nm.…”

Improved transport properties for ZnO films on Al2O3(11$\bar2$0) by MOCVD

“…On the other hand, Metalorganic chemical vapor deposition (MOCVD) has great advantages in terms of large-area deposition, atomic composition control feasibility, and high deposition rates [6]. However, good transport properties for ZnO films had not been provided by MOCVD [7,8] ) and a high mobility (~170 cm 2 /Vs) for ZnO films (~2000 nm in thickness) on Al 2 O 3 substrates by CVD with the help of catalytically-produced excited water [9]. However, the requirement of a nozzle of precursors prevents a large-area deposition.…”