We report on the photoresponse in MnSe films of different compositions, thickness and deposition parameters in the wavelength range 320-900 nm. Films deposited at lower substrate temperature and with higher selenium content exhibit higher photoresponse for all wavelengths. The photoresponse curves exhibit size effect.
Chalcogenide films have been studied extensively in recent years in view of their unusual magnetic, optical and thermoelectric properties. They are used as thermoelectric generators, thin film transistors, strain sensitive devices and infrared devices [1-3]. Of these, manganese chalcogenides such as MnTe [4,5] and MnSe [6,7] films are promising materials for possible applications in photoconducting and semiconducting devices.
Recent experimental studies on MnSe crystals show that they are semiconducting both below and above Neel Temperature TN (about 150 K) [7]. Solubility limits of selenium in manganese are narrow [4]. X-ray diffraction studies [4] reveal that selenium forms two types of compounds, namely, MnSe and MnSe2. MnSe exists in three phases viz. a, fl and 7, where a and/3 are of cubic structure, while the stable 7 phase is of hexagonal structure.
In this letter, we report on the photoconducting properties of MnSe films of different atomic compositions deposited at different substrate temperatures (Ts) in the thickness range 30-150 nm.
MnSe films were prepared by thermal evaporation, on glass substrates held at different substrate temperatures, and in a vacuum of 10 -4 Pa. Prior to evaporation, the vacuum chamber was baked at 473 K and ion bombardment was used to degas the vacuum chamber. The compound formation process was accelerated by