Energetic Beam Synthesis of Dilute Nitrides and Related Alloys

Group III–V dilute nitrides, III-N _x −V_1−x (with x up to 0.10) have exhibited many unusual properties as compared to conventional semiconductor alloys. Here we review studies on the synthesis of group III–V dilute nitrides by a highly nonequilibrium method: the combination of ion implantation, pulsed-laser melting (PLM), and rapid thermal annealing (RTA). Using this method, the formation of a wide variety of III−N _x −V_1−x alloys including GaN _x As_1−x , InN _x P_1−x , Al _y Ga_1−y N _x As_1−x , and GaN _x As_1−x−y P _y has been synthesized and their optical properties investigated. In particular, ion implantation followed by PLM has been successful in forming thermally stable thin films of GaN _x As_1−x with x as high as 0.016 and structural and optical properties comparable to films grown by epitaxial deposition techniques with similar substitutional N content. Using the implantation, PLM technique group II–VI dilute oxide (II−O−VI) semiconductors, a direct analogue of the III–V diluted nitrides, have also been formed. In Zn_1-x Mn _x Te, where the O level lies below the conduction band edge, it was demonstrated that incorporation of a small amount of oxygen leads to the formation of a narrow, oxygen-derived band of extended states located well below the conduction band edge of the ZnMnTe matrix. The three absorption edges of this material (̃0.73, 1.83, and 2.56 eV) cover the entire solar spectrum providing a material envisioned for the multiband, single junction, high-efficiency photovoltaic devices.