Investigation of Indium Tin Oxide (ITO) films for the VCSEL laser with dielectric Bragg reflectors

Abstract

This paper investigates ITO films for the VCSEL (vertical cavity surface emitting laser) lasers emitting at 1000 nm band. Looking for low-resistance VCSEL structures a new laser with dielectric distributed Bragg reflectors (DBR) and ITO films was designed. Here we examine the influence of deposition process parameters on the optical and electrical parameters of ITO films. These films were deposited using the dc magnetron sputtering system with In2O3/SnO2 (90/10) source. After annealing at 500 °C, the transmittance of tested ITO films was in the range of 84%–98% for the 1000 nm wavelength, whereas the resistivity of all samples of the order of tens of μΩcm. The refractive index of ITO films, measured for 1000 nm, does not depend on the partial pressure of argon and oxygen, but depends on the deposition rate. For 180 nm/min deposition rate the refractive index is about 2, whereas for 70 nm/min – only 1.75. Surface of ITO films was smooth (roughness Ra is of the order of several tens of Å). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)