Terahertz spectroscopy of InMnAs – Jason Deibel
Date: Mon. November 13th, 2006, 12:30 pm-1:30 pmLocation: Rockefeller 221
Diluted magnetic semiconductors (DMS’s) based on III-V semiconductors such as GaAs and InAs have drawn considerable interest over the past two decades as possible materials for use in spintronic devices. These are devices in which both the charge and spin of the electron are exploited. Future DMS-based devices could include hard drives, spin-based transistors, and magnetic random access memory (MRAM). In order for such applications to be realized though, a detailed understanding of the carrier dynamics and spin magnetism of DMS’s must be developed. For magnetic semiconductors such as GaMnAs and InMnAs, it is crucial to study the influence of the Mn dopant on the electronic and optical characteristics of the parent semiconductor. Terahertz spectroscopy is a powerful technique capable of providing a detailed evaluation of a materials frequency and temperature dependent properties including absorption and conductivity. This presentation will present results from two types of types of spectrocopic measurements utilized to study InMnAs. The first, known as terahertz emission spectroscopy, uses an ultrafast laser pulse to photoexcite the InMnAs, resulting in charge-carrier acceleration and the emission of a terahertz pulse. The carrier dynamics of the InMnAs can be evaluated by examining the time-domain characteristics of the terahertz pulse. It will be shown that terahertz emission from InMnAs is strongly temperature dependence with features seen in only a few other semiconductors. The second half of the talk will present results from broadband (bandwidth > 7 THz) terahertz spectroscopy measurements of InMnAs. These transmission spectroscopy results will show that the temperature-dependent transmission varies with the percentage of Mn dopant present in the sample. The talk will conclude with a brief summary of other current research projects involving terahertz science at Rice University.