Detection in short-wave infrared (SWIR) has become a very stringent technology requirement for developing fields like hyperspectral imaging or climate changes. In a market dominated by III–V materials, GeSn, a Si compatible semiconductor, has the advantage of cost efficiency and inerrability by using the mature Si technology. Despite the recent progress in material growth, the easy fabrication of crystalline GeSn still remains a major challenge, and different methods are under investigation. We present the formation of GeSn nanocrystals (NCs) embedded in oxide matrix and their SWIR characterization. The simple and cost-effective fabrication method is based on thermal treatment of amorphous (Ge1–x Sn x ) y (SiO2)1–y layers deposited by magnetron sputtering. The nanocrystallization for Ge1–x Sn x with 9–22 at. % Sn composition in SiO2 matrix with 9% to 15% mole percent was studied under low thermal budget annealing in the 350–450 °C temperature range. While the Sn at.% content is the main parameter influencing the band-structure of the NCs, the SWIR sensitivity can be optimized by SiO2 content and H2 gas component in the deposition atmosphere. Their role is not only changing the crystallization parameters but also to reduce the carrier recombination by passivation of NCs defects. The experiments indicate a limited composition dependent temperature range for GeSn NCs formation before β-Sn phase segregation occurs. NCs with an average size of 6 nm are uniformly distributed in the film, except the surface region where larger GeSn NCs are formed. Spectral photovoltaic current measured on SiO2 embedded GeSn NCs deposited on p-Si substrate shows extended SWIR sensitivity up to 2.4 μm for 15 at. % Sn in GeSn NCs. The large extension of the SWIR detection is a result of many factors related to the growth parameters and also to the in situ or ex situ annealing procedures that influence the uniformity and size distribution of NCs.

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The electrical properties of nonirradiated and electron irradiated structures, containing a polycrystalline thin layer of CdS, sandwiched between two gold electrodes, were investigated. The thin films of CdS, obtained through thermal-vacuum evaporation on the glass substrate at a temperature of 220 °C, were subjected to two sessions of irradiation with 7 MeV electrons to the fluences of 4×1015 and 6×1015 e/cm2, respectively. In the case of nonirradiated structures, under low voltages, the Ohm’s law is followed with a thermally activated electron concentration of n0≅3×1016 cm−3, an electron mobility μ0≅0.1 cm2/V s and a room temperature electrical conductivity σ0≅4×10−4 Ω−1 cm−1. In this range of voltage the electron irradiation induces a small increase in the activation energy of mobility, determining, of course, a small decreasing of the mobility. At high-applied voltage, there is a space-charge-limited conductivity controlled by a single trap level having the depth of Ec−Et≅0.086 eV and the total trap concentration Nt≅8.9×1015 cm−3. In this range of voltage, the electron irradiation modifies the trap distribution. After the first session of irradiation a uniform trap distribution appears and after the second session, an exponential trap distribution was induced in the band gap of CdS layer. All the induced trap distributions are characterized and their effect on the charge transport mechanisms is discussed.

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