Optical and photodetector properties of stripe-like InS crystal

Stripe-like InS crystals have been grown by physical vapor transport method. Transmission electron microscopy, scanning electron microscopy, optical microscope and Raman measurement characterize the outline shape and orthorhombic structure of the as-grown InS. A prototype photo-metal-semiconductor-field-effect transistor (Photo-MESFET) has been made by a stripe and layer-like InS crystal with Ag for the drain and source contacts and Au for the gate metal. Transmittance results determine its band gap, and the value of about 1.78 eV renders InS more sensitive to near infrared (NIR) than to visible-light optical response. V-SD-I-SD measurements show p-channel conduction behavior of the InS Photo-MESFET. Under the illumination of a tungsten lamp of power density similar to 3 mW cm(-2), the trans-conductance gain reaches g(m) = 0.272 +/- 0.005 mu A V-1.