Jiagui Zheng

AlSb THIN FILMS PREPARED BY DC MAGNETRON SPUTTERING AND ANNEALING

Aluminum antimonide (AlSb) is thought to be a potential material for high efficiency solar cells. In this paper, AlSb thin films have been fabricated by DC magnetron sputtering on glass substrates. The sputtering target consists of aluminum and antimony, and the area ratio of Al to Sb is 7:3, which is derived from research into the relationship between the deposition rates of both the metals and sputtering power. XRD and AFM measurements show that the as-deposited films are amorphous, but become polycrystalline with an average grain size of about 20 nm after annealing in an argon atmosphere. From optical absorption measurements of annealed AlSb films, a band gap of 1.56 eV has been demonstrated. Hall measurements show that the films are p-type semiconductors. The temperature dependence of dark conductivity tested in vacuum displays a linear lnσ to 1/T curve, which indicates a conductivity activation energy of around 0.61 eV.

Structure and optical properties of polycrystalline Cd1−xZnxTe thin films prepared by simultaneous evaporation

Cd1−xZnxTe films were deposited by simultaneous evaporation of CdTe and ZnTe. These Cd1−xZnxTe films were of cubic phase, and strongly (1 1 1) oriented as deposited. Predominant direct optical transitions were observed and the band gap varied with zinc content in a non-linear way. A structure development of CdS/CdTe/ZnTe : Cu solar cells with a Cd1−xZnxTe buffer layer was proposed.

STUDY ON AlSb POLYCRYSTALLINE THIN FILMS PREPARED BY VACUUM CO-EVAPORATION

In this paper, the AlSb polycrystalline thin films were prepared by vacuum co-evaporation technology and their structural, optical and electrical properties have been studied. XRD results showed that the as-deposited AlSb amorphous thin films transformed to polycrystalline state after annealed in vacuum at temperatures higher than 540°C. The process of phase change was observed to depend on the annealing temperature and the film composition. Some irreversible changes took place in the annealed films during the measurement of the temperature dependence of the film conductance. The conductance activation energy of the film was 0.132 and 0.32 eV during the heating and cooling process, respectively, which suggests the decrease of Sb vacancies in the AlSb film after the heating. Hall effect and optical absorption measurement showed that the AlSb polycrystalline thin films were p-type, indirect bandgap semiconductors with absorption coefficient higher than 8 × 104cm-1. TCO/CdS/AlSb photovoltaic devices with the local open circuit voltage of over 200 mV have been fabricated.

Produce Technology of CdTe Thin Film Modules and Design of Manufacture Line

Cadmium telluride thin films solar cells and modules have demonstrated high performance and low cost. After the efficiency of CdTe thin film solar cell made in Sichuan University reached 13.38%, a task of translation from the laboratory to pilot production of the solar cells has begun by us. The structure of the cells is CdS/CdTe/ZnTe/ZnTe:Cu. The front electrode is SnO2:F/HR-SnO 2 films on soda-lime glass and the metal as back electrode is Ni. This paper introduces the main manufacture technologies of our CdTe thin film solar modules with 300 mmtimes400 mm, explains the designs of the key equipments for 0.3 MW/year pilot manufacture line. According to the produce technologies implemented with the equipments, we estimate the costs of materials and modules. The result is that the cost of 1 W p CdTe PV module would be 1.8 dollar

Electrical Properties of Si-Doped AlSb Polycrystalline Films by Co-Sputtering

Si-doped AlSb polycrystalline films were grown on silex by magnetron co-sputtering. The conducting type, Hall mobility and carrier concentration of the films were determined. The films appear to be p-type indicating Si is shown to be predominantly an acceptor in AlSb, and holes as dominant charge carriers. Scanning electronic microscope (SEM) shows that prepared film is uniform and compact. The conductivity activation energy calculation result reveals the Si acceptor level is very close to the top of the valence band.

The Influence of Preparing Conditions on the Properties of CdS Polycrystalline Thin Films Prepared by Magnetron Sputtering

CdS polycrystalline thin films were fabricated by magnetron sputtering and the influence of substrates, sputtering powers, pressures, and substrate temperatures on the structure of thin films is investigated. The films deposited on substrates of glass, quartz, SnO 2 : F and p-type single silicon are hexagonal phase and they grow preferentially along (002) planes. As the radio-frequency power and substrate temperature increase, the preferential growth is improved, while it is decreased with the increases of pressure especially over 0.2 Pa. In addition, annealing in air or N 2 or with CdCl 2 can increase the grain size greatly and promote preferential growing.

The Electrical and Optical Properties of CSS CDTE Thin Films Deposited in AR+O2 Atmosphere

The fabrication and properties of CdTe layer are most important to the performance of CdTe thin film solar cells, among their several function layers. In the paper, a technology of closed-space sublimation(CSS) in Ar+O2 atmosphere has been studied and a method of depositing CdTe thin films on smooth glass substrate has been developed. The structural properties of these films deposited in an appropriate CSS process have been investigated by XRD and SEM, which show that there are some changes by different abrading times. Then, the optical and electrical properties of CdTe films deposited on glass in different fractional pressure of O2 have been studied, and the effects of post-treatment on the properties are observed. These results have been used to prepared CdS/CdTe/ZnTe:Cu solar cells. FF of 70.3% and efficiency of 13.38% have been demonstrated for 0.501cm2 cell