Effect of indium low doping in ZnO based TFTs on electrical parameters and bias stress stability

Journal Article · Sun Nov 15 04:00:00 EST 2015 · AIP Advances

DOI:https://doi.org/10.1063/1.4935789· OSTI ID:22492181

Kuznetsov, Sergey N.; Stefanovich, Genrikh B. ^[1]

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1. Physico-Technical Department, Petrozavodsk State University, Petrozavodsk 185910 (Russian Federation)

Some applications of thin film transistors (TFTs) need the bottom-gate architecture and unpassivated channel backside. We propose a simple routine to fabricate indium doped ZnO-based TFT with satisfactory characteristics and acceptable stability against a bias stress in ambient room air. To this end, a channel layer of 15 nm in thickness was deposited on cold substrate by DC reactive magnetron co-sputtering of metal Zn-In target. It is demonstrated that the increase of In concentration in ZnO matrix up to 5% leads to negative threshold voltage (V{sub T}) shift and an increase of field effect mobility (μ) and a decrease of subthreshold swing (SS). When dopant concentration reaches the upper level of 5% the best TFT parameters are achieved such as V{sub T} = 3.6 V, μ = 15.2 cm{sup 2}/V s, SS = 0.5 V/dec. The TFTs operate in enhancement mode exhibiting high turn on/turn off current ratio more than 10{sup 6}. It is shown that the oxidative post-fabrication annealing at 250{sup o}C in pure oxygen and next ageing in dry air for several hours provide highly stable operational characteristics under negative and positive bias stresses despite open channel backside. A possible cause of this effect is discussed.

• OSTI ID: 22492181
• Journal Information: AIP Advances, Journal Name: AIP Advances Journal Issue: 11 Vol. 5; ISSN AAIDBI; ISSN 2158-3226
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABUNDANCE
AGING
ANNEALING
CONCENTRATION RATIO
DOPED MATERIALS
ELECTRIC POTENTIAL
INDIUM
LAYERS
MATRIX MATERIALS
MOBILITY
OXIDATION
OXYGEN
SPUTTERING
SUBSTRATES
THIN FILMS
TRANSISTORS
ZINC OXIDES