Magneto-optic effects in doped InP Maarij Syed * , Azad Siahmakoun Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN, 47803, USA Received 10 February 2004; accepted 22 June 2004 Available online 22 December 2004 Abstract We report on the investigation of Faraday rotation (FR) of indium phosphide (InP) conducted for several different wavelengths at room temperature. Appreciable FR, yielding Verdet constant values at 980, 1064, 1320, and 1550 nm at room temperature, has been observed. We have also investigated the role for dopants in FR for this class of materials. Specifically we have investigated an n-type dopant (Sulfur) and p-type dopants (Cd and Fe). We also present a simple and consistent model that explains the results for sulfur and points to the need for a more systematic study of these materials. Ó 2004 Elsevier B.V. All rights reserved. PACS: 78.20.Ls; 33.55.Ad; 78.66.Fd Keywords: Indium phosphide; Dopants; Magneto-optics; Faraday rotation; Band gap; Spectroscopic ellipsometry 1. Introduction InP is a compound material. Like Galium Arsenide (GaAs), it belongs to the III–V family of materials. While GaAs may be the better known member of the III–V family, interest in InP has been steadily growing for the past twenty years. This growing interest is due to the present applications and future potential of InP in high-speed electronics and long-haul fiber optics com- munication. InGaAsP/InP multiple quantum wells are fast becoming the material of choice for long distance fiber optic communication due to the tunability of its en- ergy gap in the wavelength that is of great interest for communications (1.31 and 1.55 lm). Active devices such as DFB lasers, optical amplifiers, and detectors already utilize the benefits of InP and its related compounds. InP is seen as a promising candidate for integrated devices where in addition to active devices, it can also be used to create passive devices like waveguides [1]. For many device applications, dopants already pres- ent or intentionally added to InP play a critical role. Unintentional doping during growth generally results in n-type behavior for InP samples. For photoreactive applications, InP is typically doped with iron (InP:Fe). This allows these samples to become semi-insulating [2]. It also allows them to have interesting magnetic properties including Faraday rotation. Faraday rotation has been established as an invaluable tool in the investi- gation of a class of materials that is referred to as diluted magnetic semiconductors (DMS) [3,4]. We have investi- gated the behavior of dopants, both intentional and unintentional, in InP and their effect on FR. Specifically, we have investigated FR in sulfur doped (InP:S) and cadmium doped (InP:Cd) samples. The iron doped sam- ples that were investigated had a small variation in their doping concentration because they were taken from dif- ferent parts of the boule. Another established area of InP research is photo- refractive (PR) behavior of InP. Typical PR experi- ments involve conventional two-wave and four-wave 0925-3467/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.optmat.2004.11.002 * Corresponding author. Tel.: +1 812 877 8957; fax: +1 812 877 8023. E-mail addresses: maarij.syed@rose-hulman.edu (M. Syed), azad. siahmakoun@rose-hulman.edu (A. Siahmakoun). www.elsevier.com/locate/optmat Optical Materials 27 (2005) 1629–1636