| With the development of the third semiconductors, there has been increasing interest in the research of wide band gap oxide semiconductor. It is a very potential material for transparent and ultraviolet optoelectronic devices, so the study of the wide band gap oxide semiconductor is enormously significant. Nowadays, the field has already been the international front of the research. Tin oxide is a wide band gap semiconductor with direct band gap. Compared with GaN and ZnO, SnO2has a wider band gap3.6eV at room temperature, and a higher exciton binding energy of130meV. In the past, the investigation of SnO2films was mainly focused on the fields of transparent conducting oxides and gas sensors. In resent years, however, there is more attention being paid to the preparation of high quality SnO2films, and the structure and photoelectric properties have been investigated in detail. The SnO2films prepared by the common methods such as sputtering and spray pyrolysis are defective, which is difficult to be used in the field of semiconductor device. Recently, several fabrication methods have been explored to grow the epitaxial SnO2thin films, which include pulsed laser deposition (PLD), atomic layer deposition (ALD) and chemical vapor deposition (CVD). Under such background, epitaxial SnO2thin films are prepared by MOCVD, which is suitable for commercial production. The structure and photoelectric properties of tin oxide films is investigated in detail. The study has both science meaning and practical application foreground.The content of this article contains two parts. In the first part, epitaxial SnO2films were prepared on TiO2(001) and MgO (100) substrate by MOCVD, and the structural and photoelectric properties of the films were investigated. In the second part, SnO2films doped with Sb were prepared on TiO2(001) and MgO (100) substrate by MOCVD, and the structural, optical and electrical properties of the films were studied systematically.The major research work and results of the first part are as follows:SnO2films were prepared on TiO2(001) and MgO (100) at different substrate temperatures by MOCVD. During the deposition processes, high purity Sn(C2H5)4(6N) was used as the MO source, high purity O2was used as the oxidant, ultra high purity N2was used as the carry gas. The structural, optical and electrical properties of the films were investigated.1. SnO2films were deposited on TiO2(001) substrate at different temperatures of500℃,600℃and700℃. Structural analyses showed that the films deposited at different temperatures were rutile structure SnO2with a single orientation of [001] direction. The epitaxial relationship between film and substrate was SnO2(002)//TiO2(002) with SnO2[010]//TiO2[010] and SnO2[100]//TiO2[100]. The optical transmittance spectra showed that the average transmittance in the visible range for all prepared films was over68%, exceeded the transmittance66%for the substrate. The photoluminescence (PL) spectrum of SnO2film deposited at600℃showed a broad band centered at615nm, and the luminescence mechanism could be attribute to the structural defects formed during the growth.2. SnO2films were deposited on MgO (100) substrate at different temperatures of500℃,550℃,600℃and700℃. XRD and HRTEM results showed that the films deposited at different temperatures were rutile structure SnO2with a single orientation of [110] direction. The schematic diagrams of the epitaxial relationships were given. Two domains were formed inside the epitaxial film deposited on MgO (100) substrate. The epitaxial relationship between the film and substrate was SnO2(110)//MgO(100) with SnO2[110]//MgO [011], SnO2[001]//MgO [011]. The Hall mobility of the film prepared at600℃was17.1cm2·v-1·s-1. The carrier concentration of the film was2.9×1018cm-3. And the resistivity of the film was0.126Q-cm. The average transmittance of the sample prepared at600℃in the visible wavelength region (380nm-780nm) exceeded77%, and the optical band gap was3.93eV.The major research work and results of the second part are as follows:SnO2:Sb films were prepared on TiO2(001) and MgO (100) at different substrate temperatures by MOCVD. During the deposition processes, high purity Sn(C2H5)4(6N) and Sb(CH3)3(6N) were used as the MO source, high purity O2was used as the oxidant, ultra high purity N2was used as the carry gas. The structural, optical and electrical properties of the films were investigated systematically.1. SnO2:Sb films were deposited a t600℃on TiO2(001) substrate with various amounts of Sb-doping (1%,3%,5%and7%). The XRD and HRTEM results indicated that the prepared samples were rutile structure SnO2with a single orientation of [001] direction. The phases of Sb2O3and Sb2O5were not been found. With the increase of antimony content, the films changed from epitaxial films to amorphous or microcrystalline. The average transmittance of all the samples in the visible wavelength region (380nm-780nm) exceeded the average transmittance of the substrate. The electrical properties of the films were investigated. As the antimony content increased from0to7%, the Hall mobility of the films decreased from18.1cm2·v-1·s-1to3.4cm2·v-1·s-1. The carrier concentration of the films increased fleetly, and then decreased slowly. On the contrary, the resistivity of the films decreased fleetly, and then increased slowly. The3%Sb-doped SnO2film exhibited the best electrical properties. The resistivity, carrier concentration and Hall mobility for the3%Sb-doped SnO2film were2.3×10-3Ω·cm,4.1×1020cm-3and6.9cm2·v-1·s-1, respectively.2. SnO2:Sb films were deposited a t600℃on MgO (100) substrate with various amounts of Sb-doping (1%,3%,5%,7%and10%). The XRD results indicated that the films were rutile structure SnO2with a single orientation of [110] direction. The average transmittance of all the samples in the visible wavelength region (380nm-780nm) exceeded77%. With the increase of antimony content, the optical gaps of the SnO2:Sb films were in the range of3.98eV-4.13eV. The electrical properties of the films were investigated. As the antimony content increased from0to10%, the Hall mobility of the films decreased from17.1cm2·v-1·s-1to6.3cm2·v-1·s-1. The carrier concentration of the films increased fleetly, and then decreased slowly. On the contrary, the resistivity of the films decreased fleetly, and then increased slowly. The3%Sb-doped SnO2film exhibited the best electrical properties. The resistivity, carrier concentration and Hall mobility for the3%Sb-doped SnO2film were1.2×10-3Ω·cm,5.4×1020cm-3and9.9cm2·v-1·s-1, respectively.
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