This work reports on processing, analysis and characterization of copper indium gallium diselenide (CIGS) used as a photosensitive layer for sensors such as sun angle detectors in space applications. CIGS-based solar cell devices with different CIGS layer thicknesses and the pn-junction located on the opposite side of the incidence of light were illuminated through their ultra-thin transparent molybdenum back contacts. The results from the current density versus voltage and quantum efficiency measurement indicate that the CIGS absorber layer may not exceed 750 nm at backside illumination, due to the limited CIGS diffusion length.

Presented here is an examination of unstructured and structured (by anisotropic etching), monocrystalline silicon wafers coated with sputter deposited aluminum and chemical vapor deposited silicon dioxide for high solar reflectance and high thermal emittance, respectively. The topography of the samples was characterized with optical and scanning electron microscopy. Optical properties were examined with reflectance and transmittance spectroscopy, partly by usage of an integrating sphere. The measurement results were used to estimate the equilibrium temperature of the surfaces in space. The suitability of the surfaces with high solar reflectance and high thermal emittance to aid in the thermal control of miniaturized, highly integrated components for space applications is discussed. A silicon dioxide layer on a metal layer results in a slightly lower reflectance when compared to surfaces with only a metal layer, but might be beneficial for miniaturized space components and modules that have to dissipate internally generated heat into open space. Additionally, it is an advantage to microstructure the emitting surface for enhanced radiation of excess heat.

This paper presents the development of a miniaturized, thin film sun sensor for sun angle detection in space applications. The overall design, different thin film layer sequences, processes, materials used and system integration are described. The sun sensor has a field of view (FoV) of greater than 2π sr (±90°) and shall have a resolution of approximately 1° in elevation and azimuth angle. This sun sensor is therefore a coarse sun sensor with the advantage of having a large field of view. Key elements are the curved shape, the photosensitive layer consisting of copper indium gallium diselenide (CIGS), the transparent conductive layer consisting of thin molybdenum or aluminum-doped zinc oxide, and its integrated design. Different possible layer sequences are presented and discussed. The sun sensor will be one of the sensors in the attitude determination and control system (ADCS) of a nano-satellite.