Correlation Between Energy Gap and Defect Formation of Al Doped Zinc Oxide on Carbon Doped Silicon Oxide

Abstract

Aluminum-doped zinc oxide (AZO) films were deposited on SiOC/Si wafer by an RF-magnetron sputtering system, by varying the deposition parameters of radio frequency power from 50 to 200 W. To assess the correlation of the optical properties between the substrate and AZO thin film, photoluminescence was measured, and the origin of deep level emission of AZO thin films grown on SiOC/Si wafer was studied. AZO formed on SiOC/Si substrates exhibited ultraviolet emission due to exciton recombination, and the visible emission was associated with intrinsic and extrinsic defects. For the AZO thin film deposited on SiOC at low RF-power, the deep level emission near the UV region is attributed to an increase of the variations of defects related to the AZO and SiOC layers. The applied RFpower influenced an energy gap of localized trap state produced from the defects, and the gap increased at low RF power due to the formation of new defects across the AZO layer caused by lattice mismatch of the AZO and SiOC films. The optical properties of AZO films on amorphous SiOC compared with those of AZO film on Si were considerably improved by reducing the roughness of the surface with low surface ionization energy, and by solving the problem of structural mismatch with the AZO film and Si wafer.

Electrical Properties of Nanoscale ZnS Thin Film Transistor

“…This result agreed with the crystalline orientation of the ZnS annealed at 100 ∘ C as previously mentioned in Figure 1(b). In particular, the strong and intrinsic PL emission peak of ZnS could be obtained on SiOC after annealing at 100 ∘ C. The high level properties of oxide semiconductors which used SiOCs were reported in the author's previous paper [28]. To analyze the relationship between the crystallinity and electrical characteristics of ZnS/SiOC, the transfer characteristics of ZnS/SiOC TFTs were measured with various drain voltages from 10 V to 0.001 V. The DS -DS was also researched to define the contact mechanism of TFTs.…”