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Carbonitride nano- arrays and p -type zinc oxide Preparation

Author: XuXiaoFeng
Tutor: XuNing
School: Fudan University
Course: Optics
Keywords: carbon nitride nanocone (CNNC) arrays ZnO:Bi thin film pulsed laser ablation deposition(PLD) direct-current abnormal glow discharge plasma reaction deposition (GPRD)
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 60
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Abstract


The content of this thesis includes two parts:the first part is synthesis of carbon nitride nanocone（CNNC） arrays on the Co intermediate layer by pulsed laser ablation deposition（PLD） and direct-current abnormal glow discharge plasma reaction deposition（GPRD）;The second part is synthesis of P-type ZnO:Bi films by pulsed laser ablation（PLD）.Since the empirical predication by Cohen et al.thatβ-C3N4 might have an exceptional hardness even higher than that of diamond,the role of nitrogen as reducing the formation energy of their carbon counterparts has been further supported by applying first-principles calculations to investigate the effect of introducing nitrogen in carbon nanostructures.It has been proposed that doping of nitrogen into graphite or diamond nanostructures,or better direct constructing carbon nitride nanostructures,can enhance their field emissivity as field emitters,increase their mechanical,thermal and chemical stability,and purposedly manipulates the electronic and optical properties by varying the relevant compositions.Here,a novel method, called GPRD,is proposed for synthesis of CNNC arrays.In our method,the Si（100） wafers were used as substrates,and a Co thin layer as catalyst were deposited on them by PLD prior to the preparation of CNNC arrays.Our method,different from the usual micro-wave plasma-assisted CVD with low density of plasma and arc-jet CVD with low voltage,combines highly-dense-plasma-assisted CVD with bias-enhancement,and is simple and easily manipulatory.The bias-enhanced highly-dense plasma containing energetic neutral and ionic nitrogen atoms and carbon-related precursors can promote the gas-phase reactions for the growth of CNNCs.One goal of our work is to identify an economic way of fabrication of the CNNC arrays for the related applications.Another goal is to achieve a reasonable level of control and predictability in the size,shape,structure,place and orientation of such CNNCs.Two main models are also proposed to explain the growth mechanism of the CNNCs.In recent years,ZnO has been investigated widely as a promising material for short-wavelength optoelectronic devices,such as UV/violet/blue light emitting diodes and laser diodes.Synthesis of high-quality n-type and p-type ZnO is the necessary step for device development.The quality of synthesized n-type ZnO is already sufficiently good for device applications.However,the growth of p-type ZnO is still rather difficult due to its self-compensation,deep acceptor level and low solubility of dopants.In this work,large-sized-mismatched group-V element Bi doped ZnO （ZnO:Bi） thin films were synthesized on Si（100） substrates by the pulsed laser deposition（PLD） method using Bi -mixed ZnO targets.The p-type ZnO thin films synthesized by using 1-3 at.%ZnO:Bi targets show stable p-type conduction with hole carrier concentration of about 1018-1019 cm-3.

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