Charge transport, optical transparency, microstructure, and processing relationships in transparent conductive indium–zinc oxide films grown by low-pressure metal-organic chemical vapor deposition

Abstract

Indium–zinc oxide films (ZnxInyOx+1.5y), with x/y=0.08–12.0, are grown by low-pressure metal-organic chemical vapor deposition using the volatile metal–organic precursors In(TMHD)3 and Zn(TMHD)2 (TMHD=2,2,6,6–tetramethyl–3,5–heptanedionato). Films are smooth (rms roughness=40–50 Å) with complex microstructures which vary with composition. The highest conductivity is found at x/y=0.33, with σ=1000 S/cm (n-type; carrier density=3.7×1020 cm3; mobility=18.6 cm2/V s; dσ/dT<0). The optical transmission window of such films is broader than Sn-doped In2O3, and the absolute transparency rivals or exceeds that of the most transparent conductive oxides. X-ray diffraction, high resolution transmission electron microscopy, microdiffraction, and high resolution energy dispersive X-ray analysis show that such films are composed of a layered ZnkIn2O3+k phase precipitated in a cubic In2O3:Zn matrix.

Studies on Structural, Optical and Electrical Properties of ZnO Thin Films Prepared by the Spray Pyrolysis Method

“…For the violet peak is attributed to free excitonic emission because of the high exciton binding energy of 60 meV. On the other hand, interface traps are reported to lie within the depletion regions located at the ZnO-ZnO grain boundaries [38] and have been found to the conduction band edge, which suggest that the observed 418 nm violet luminescence is due to associated radiative defects and green emission is commonly observed for ZnO, and is attributed to oxygen deficiency [36,37]. …”

Preparation and characterization of highly transparent and conductive indium-zinc oxide thin films deposited by pyrolysis spray technique

“…In particular, the indium-zinc oxide system has attracted considerable attention as promising materials for transparent conducting films. Indium-zinc oxide films have been prepared using sputtering (Minami et al 1996a, b), Metal Organic Chemical Vapour Deposition (Wang et al 1998) and Laser Deposition (Phillips et al 1995;Zheng and Kwok 1993), but rarely, multi-compound oxides have been prepared by simples methods like spray pyrolysis which is low cost, and offer the possibility to produce large area layers desirable for solar and electrochromic applications. Another advantage of this technique is the facility to prepare homogeneous thin films when doping is required.…”

Indium zinc oxide thin films deposited by sputtering at room temperature

“…Security applications include inexpensive flexible sensors networked to provide monitoring over large areas. Amorphous n-type oxide semiconductors have shown promising results for situations where the standard Si-based thin film transistors (TFTs) have drawbacks such as light sensitivity, light-induced degradation and low field effect mobility (<1 cm 2 V À1 s À1 ) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Materials such as zinc oxide, indium gallium oxide and zinc tin oxide show surprisingly high electron mobilities ($10 cm 2 V À1 s À1 ) even for amorphous films deposited at room temperature or slightly above.…”