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High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded alpha-plane sapphire at low temperature

Jayah, Nurul Azzyaty and Yahaya, Hafizal and Mahmood, Mohamad Rusop and Terasako, Tomoaki and Yasui, Kanji and Hashim, Abdul Manaf (2015) High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded alpha-plane sapphire at low temperature. Nanoscale Research Letters, 7 (2). ISSN 1556-276X

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Official URL: http://dx.doi.org/10.1186/s11671-014-0715-0

Abstract

Hydrothermal zinc oxide (ZnO) thick films were successfully grown on the chemical vapor deposition (CVD)-grown thick ZnO seed layers on alpha-plane sapphire substrates using the aqueous solution of zinc nitrate dehydrate (Zn(NO3)(2)). The use of the CVD ZnO seed layers with the flat surfaces seems to be a key technique for obtaining thick films instead of vertically aligned nanostructures as reported in many literatures. All the hydrothermal ZnO layers showed the large grains with hexagonal end facets and were highly oriented towards the c-axis direction. Photoluminescence (PL) spectra of the hydrothermal layers were composed of the ultraviolet (UV) emission (370 to 380 nm) and the visible emission (481 to 491 nm), and the intensity ratio of the former emission (I-UV) to the latter emission (I-VIS) changed, depending on both the molarity of the solution and temperature. It is surprising that all the Hall mobilities for the hydrothermal ZnO layers were significantly larger than those for their corresponding CVD seed films. It was also found that, for the hydrothermal films grown at 70 degrees C to 90 degrees C, the molarity dependences of I-UV/I-VIS resembled those of mobilities, implying that the mobility in the film is affected by the structural defects. The highest mobility of 166 cm(2)/Vs was achieved on the hydrothermal film with the carrier concentration of 1.65 x 10(17) cm(-3) grown from the aqueous solution of 40 mM at 70 degrees C.

Item Type:Article
Uncontrolled Keywords:carrier concentration, zinc oxide
Subjects:T Technology > TJ Mechanical engineering and machinery
Divisions:Malaysia-Japan International Institute of Technology
ID Code:55574
Deposited By: Fazli Masari
Deposited On:20 Sep 2016 01:16
Last Modified:15 Feb 2017 04:01

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