Emergy evaluation of a traditional farming system. Case study: Leh District (Ladakh - Indian Trans-Himalaya)

Abstract

Group-IV diluted magnetic semiconductor (DMS), Si:Ce thin films with Ce concentration below 4.0 at% were grown by low-temperature molecular beam epitaxy (LT-MBE) on (0 0 1) Si substrates. Low-temperature growth enables uniform distribution of Ce in Si without hillock and pit formations. Smooth surface and abrupt interface of Si:Ce thin film grown at the growth temperature of 430 °C were observed. Magnetic properties of Si:Ce thin films were investigated by a superconducting quantum interference device (SQUID). All the samples exhibited positive magnetization at 4.2 K. The ferromagnetic interaction was enhanced when the Si:Ce film had p-type conduction. However, the film with n-type conduction also exhibited ferromagnetic behavior when the film included high Ce concentration above 4.0 at%. © 2006 Elsevier B.V. All rights reserved.