Complete photo-generated minority carrier's quantum tunneling device under AM1.5 illumination is fabricated by depositing tin-doped indium oxide (ITO) on n-type silicon to form a structure of ITO/SiOx/n-Si heterojunction. The work function difference between ITO and n-Si materials essentially acts as the origin of built-in-field. Basing on the measured value of internal potential (Vbi = 0.61 V) and high conversion efficiency (9.27%), we infer that this larger photo-generated holes tunneling occurs when a strong inversion layer at the c-Si surface appears. Also, the mixed electronic states in the ultra-thin intermediate region between ITO and n-Si play a defect-assisted tunneling.
In this short report, the specific molecular coacervate and two kinds of quantum states in indium-involved amorphous silicon oxide [a-SiOx(In)] are studied. The a-SiOx(In) layer is prepared by the magnetron sputtering process for indium tin oxide (ITO) films deposited on n-type silicon substrates, which has been predicted by molecular dynamics simulation and density function theory calculation. The results have been applied to the interpretation of the electronic structure and hole tunneling transport in ITO-SiOx/n-Si photovoltaic (PV) devices. The most significant achievement is that there is either a transition level at 0.30 eV for p-type conductive conversion or an extra level at Ev + 4.60 eV induced by In-O-Si bonding, denoted as molecular orbital levels, within the dielectric amorphous oxide (a-SiOx). The cognizance is crucial for the concepts of passivation, tunneling, selective contact, inversion, and useful defects in modern PV devices.
First-principles calculations have been performed to study the adsorption of Aluminium(Al) on the Si(001)2×1 surface. The optimized geometries and electronic structures of the adsorption system were investigated. The adsorption energy at various adsorption coverages(Θ) from half a monolayer(ML) to one monolayer has been calculated. The most stable adsorption sites were consequently determined to be HH site and T3-T4 site, respectively. There is obvious evidence that the asymmetric aspect of the Si-Si dimer becomes the symmetric one which has been observed at the coverage of 0.5ML or 1ML. In addition, the bond length of Si-Si was found to be considerably elonged upon the Al adsorption. The work function calculations have shown that the aspect of work-function change for the Si(001) surface due to the adsorption of Al is different from that of the alkali metals adsorption reported in some previous works. The surface formation energy was also calculated. The absolute value of the surface formation energy was found to decrease with increasing coverage indicating that 1ML is not a saturation coverage. In order to shed light on the nature of the Al-Si bond and the character of silicon surface, the density of states and band structure of the system were calculated. 1. INTRODUCTIONIn the recent decades, the metal/Silicon surface systems have gained much attention. Many experiments have been carried out to study these systems with various techniques of low-energy electron diffraction (LEED), high-energy electron diffraction (HEED), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). The group-Ⅲ metal/Si(100) systems[1,2] have been widely investigated. We expect that the reaction mechanisms of the two systems will help us in understanding the behavior of III-V compounds growing on the Si surface. Nogami et al [1]. have studied the growth of the first monolayer(ML) of Al on Si(100) with scanning tunneling microscopy(STM). They have pointed out there were actually two configurations in which the Al dimers were positioned either perpendicular or parallel to the underlying Si dimers. But they haven't clarified the bonding site of the Al dimers on this surface. Brocks et al [2]. have shown that the adsorption of Al onto the Si(100) surface can be described by a reaction mechanism. They pointed out that the clean Si(100) surface was most stable consisting of "buckled" Si dimers. In contrast to this components, Chao et al [3]. have observed the Cs-saturated surface still has asymmetric dimers with method of photoelectron spectroscopy. Baski et al [4]. have studied Sn-induced reconstructions of the Si(100) surface using LEED and STM. In the experiment, they believed that the metal dimer bond could in fact be oriented parallel to the underlying Si dimer bonds. Umeno and Kitamura[5] examined Al/Si systems by ab initio molecular dynamics (MD) calculations. Their results suggested that the dense layers of Al could be formed on the surface. Up to now periodic density functional theory(DFT) have been widely and suc...
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