Photoluminescence And Nonlinear Optical Study Of Diluted Magnetic Semiconductor (GaMn)N

This paper concentrates on the optical properties of diluted magnetic semiconductor (DMS) (GaMn)N. DMS have recently arisen considerable interesting for creating a class of"spintronic"semiconductor devices with unprecedented functionality. Particularly, (GaMn)N is a very promising material as a candidate of DMS, since its Curie temperature exceeds room temperature and GaN-based devices have wide applications in the area of high-temperature and big power optoelectronic devices.First we review the studies of the (GaMn)N, including the mechanisms of ferromagnetism, as well as the magnetic, optical, and electrical properties. Since the up-to-date optical properties are still limited and deficient, the majority of our work is assigned to the following aspects: the photoluminescence (PL) characteristics, their dependence on temperature, excitation power and Mn-implantation doses and nonlinear optical properties. The nonlinear optical properties of semiconductors were intensively used in the optoelectronic devices, such as all-optical switches, optical limiters and waveguide formation etc. The investigation of nonlinear optical materials is a hot topic in theoretical and experimental research at all times. Therefore the study of nonlinear optical characteristic of semiconductor is of very important and has practical significance. We employ the ion-implantation method to produce a series of (GaMn)N samples. Their structural properties and the dependence of the lattice constants on Mn-implantation doses are discussed. And then we introduce the fundamentals of the experiments on studying the spectra of semiconductors, i.e., the Raman scattering, PL spectra, and Z-scan technology. We also briefly describe the instruments and apparatus used in our studies.We focus on the PL characteristics on (GaMn)N. By the room temperature PL spectra and Hydrogen-model calculation of the effective mass, we reveal the Mn-related transitions and these origins. Furthermore, the temperature, Mn-implantation doses and excitation-intensity dependent PL spectra are studied to investigate the localization effects in (GaMn)N.Optical nonlinearities of GaN and (GaMn)N thin film were investigated by the reflection z-scan method using a mode-locked femtosecond Ti:sapphire laser. Using a simple model, we get the nonlinear refractive index of (GaMn)N which is minus. It firstly increases and then decreases with the Mn-implantation doses increasing. The Mn-implantation doses dependence of the measured n2 value indicate that the nonlinear refractive index of (GaMn)N will get the maximum when the Mn-implantation doses become the critical concentration.This work is supported by the Natural Science Foundation of China (under contract Nos. 10304010,10774100,1067404 and 10734020), Shanghai Municipal Commission of Science and Technology, and the National Minister of Education Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT) (contract No. IRT0524).