In Situ Sensors for CIGS Deposition and Manufacture
- PDF / 222,140 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 50 Downloads / 170 Views
F15.3.1
In Situ Sensors for CIGS Deposition and Manufacture I.L Repins, N. Gomez, L. Simpson, B. Joshi ITN Energy Systems; Littleton, CO 80127 ABSTRACT In situ sensors are an important tool for process control, optimization, and documentation, both in the laboratory and industrial environments. Their further application to deposition of CuInxGa1-xSe2 (CIGS) for photovoltaics is particularly important, as record device efficiencies produced in the laboratory have yet to be replicated in manufacturing. This paper provides an overview of the current state of the art of in situ diagnostics for devices based on coevaporated CIGS. INTRODUCTION In situ sensors are useful for several reasons. At the most basic level, they allow reproducible establishment of deposition conditions such as rates, temperatures, or gas flows. In situ diagnostics are also important for process optimization: Sensing important film properties in real time provides immediate feedback for assessing the benefit of intentional process changes. Furthermore, in situ sensors can document a history of important film properties and deposition conditions. Such a history is an important tool in transferring processes to different chambers or troubleshooting an existing process (e.g. determining whether an unexpected reduction in performance is due to a failure during the CIGS deposition or some later processing step). For industrial applications, in situ sensors can be used for process control, to keep product quality within an acceptable window. Such applications of sensors also reduce costs, both through increased yield and identification of sub-standard material that need not be sent through subsequent processing steps. Nowhere are the needs for in situ diagnostics greater than for CIGS where record devices in the laboratory have surpassed 19%,1 but the efficiencies obtained by industry for modules fabrication are substantially lower. In situ diagnostics can be used to both document the necessary film properties and process conditions for very high efficiency devices, as well as then keep process conditions and product quality within the prescribed window. This paper provides an overview of the current state of the art for in situ diagnostics for devices based on co-evaporated CIGS. Deposition by co-evaporation is chosen as the subject of this paper because it has created record efficiency devices,1 and is one of the most demanding environments for sensors. It requires simultaneous control of multiple flux species, as well as operation at high temperatures (500 to 575 oC) in the presence of Se vapor. Because of these stringent requirements, many sensors that are effective during CIGS coevaporation are likely to be applicable to a number of other CIGS deposition techniques as well. An overview and comparison of the available sensors for absorber and device fabrication, and of unfilled needs in the area, is presented.
F15.3.2
REQUIREMENTS FOR IN SITU SENSORS Before reviewing the available options for in situ sensors, it is useful to discuss the general r
Data Loading...
