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In this work, we present results on simultaneous formation of emitter/back-surface field or emitter/surface passivation in a single rapid thermal cycle. We have investigated the diffusion kinetics of dopant elements like phosphorus, boron (from a doped spin-on glass (SOD) film), aluminium (from evaporated films) or aluminium-boron (from an A1-B SOD film). In particular, we have shown that rapid thermal co-diffusion of P and A1 (or A1-B) leads to low sheet resistances, optical emitter profiles and a hig h gettering effect. Furthermore, the possibility of using the remaining SOD films as a surface passivation layer was investigated. Dark saturation current measurements as deduced from the photoconductivity decay technique demonstrate the passivation effec t of the remaining SOD film. The highest efficiency of 12.8% obtained was achieved on SOD oxide-coated solar cells.

Epitaxial growth of silicon films over the temperature range from 900 to 1300 °C was investigated in a rapid thermal chemical vapour deposition reactor working at atmospheric pressure. The growth of boron doped Si was performed from trichlorosilane and trichloroborine diluted in hydrogen. The epilayers were analysed by Rutherford backscattering spectroscopy, specular reflectance, scanning electron microscopy and Nomarski microscopy. Mechanisms for the observed growth rate are examined, and are tied closely to the degree of surface coverage by Cl. The electrical properties of the deposited films were also checked using the spreading resistance and the four point probe techniques.

In this paper, the authors investigate the simultaneous processing of the emitter junction and the emitter surface passivation by rapid thermal annealing (RTA) from a doped spin-on glass (SOG). Test structures and solar cells of different emitter profiles and surface concentrations were made by diluting two different doped spin-on glass liquids with methanol. By this procedure, oxide thickness and doping can be controlled. RTA was performed in an argon atmosphere in the temperature range of 850/spl deg/C-1000/spl deg/C for 5-60 sec. The results show that emitter surface doping concentration between 1*10/sup 19/ cm/sup -3/ and 3*10/sup 20/ cm/sup -3/ and junction depth from 0.1 /spl mu/m could be obtained. Sheet resistances lower than 150 /spl Omega///spl square/ could be easily reached. External quantum efficiency measurements from solar cells, made from CZ and FZ p-type silicon wafers, demonstrate the passivation effect of the remaining SOG-film. The highest efficiency obtained with this ohmic back contacted cells, which had an oxide thickness of about 70 nm, are 12.8%.

Rapid thermal processing (RTP) using halogen tungsten lamps as a heating source has been successfully applied to the formation of solar cells in one thermal cycle. Here, the authors extend the use of RTP to form high/low doped regions using the properties of the emitting light. They have played with the absorption, reflection and transmittance of the light in order to control the impinging radiation onto the silicon samples. Selective emitters were prepared by these procedures. Sheet resistance variations in the range 20-150 /spl Omega///spl square/ were obtained depending on the processing parameters like lamp power, time and masking procedures.

Limiting thermal exposure time using rapid thermal processing (RTP) has emerged as a promising simplified process for microelectronics applications and for manufacturing of terrestrial solar cells in a continuous way. Especially, rapid thermal diffusion (RTD) of phosphorus from doped oxide films (SOD) was extensively used for the emitter formation purpose but few work concerned the diffusion mechanism. Here we investigate more in details the diffusion kinetics of phosphorus after rapid thermal annealing of P-SOD coated silicon samples. The observed enhanced distribution of phosphorus after RTD is discussed based on the dopant sources and processing conditions. Comparisons between experimental profiles and simulation results using up to date phosphorus diffusion models allow us to discriminate between various possible enhancement mechanisms.

The rapid thermal annealing of doped (SOD) and undoped (SOG) glass films spinned onto silicon from diluted or undiluted solutions has been investigated. The dilution performed by methanol has allowed to obtain oxide films as thin as 10 nm.The optical measurements of annealed SOG films have shown that good oxide films without oxygen deficiency are achievable. The electrical characteristics of Al-gate capacitors assessed by Capacitance-voltage measurements have shown a great dependence of the water content in the range of 600–850°C before reaching a typical dielectric constant value near 3.8 at higher temperatures. Low Interface state densities values obtained at temperature up to 900°C confirm the curing effect of a rapid thermal annealing.On the other hand, we have demonstrated that the efficiency of rapid thermal diffusion from boron or phosphorus SOD films deposited on Si wafers depends on the source composition and its thickness. In particular, we have shown that it is possible to control the junction depth, the surface concentration and the minority-carrier diffusion length by varying the amount of dopant concentration in the solution, the thickness of the doped oxide film and the rapid thermal processing parameters. Futhermore, the remaining doped SOG film can play the role of an efficient oxide passivation layer.

Limiting thermal exposure time using Rapid Thermal Processing (RTP) is now emerging as a promising simplified process for manufacturing of terrestrial solar cells in a continuous way. In this work, we present results on simultaneous formation of emitter, back-surface field and surface passivation in a single rapid thermal cycle. Spin-on dopants (SOD) solutions are used as dopant sources. Optimal emitter profiles, low sheet resistances and high gettering effect are reached. The residual SOD film is used as a surface passivation layer. Solar cells with efficiencies in the range 10 – 14 % are obtained depending on temperature and time processing.