Advisory Committee Chair
Sergey B Mirov
Advisory Committee Members
Christopher M Lawson
Date of Award
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Middle-infrared lasers operating over a “molecular fingerprint” 2-15 μm spectral range are in great demand for a variety of applications. One of the best choices for lasing in the 2-5 μm spectral range is direct oscillation from divalent transition metal ions (TM2+: Cr2+, Fe2+, Co2+)-doped wide bandgap II-VI semiconductor crystals. There are three major objectives in this dissertation: 1) Realize and study middle-infrared electroluminescence of n and p-type, Cr doped bulk ZnSe crystals. We have demonstrated a method of ZnSe crystals thermal-diffusion doping with donor (In, Zn, and Al) and acceptor (Cu, Ag, and N through CrN) impurities resulting in n and p-type conductivity of Cr:ZnSe. We are the first to our knowledge to obtain mid-IR electroluminescence in nominally p-type Cr:Ag:ZnSe, which could prove valuable for developing of novel mid-IR laser diodes. 2) En route to low dimensional gain material, develop simple method for making microscopic laser active Cr doped ZnSe, ZnS and CdSe powders, realize and study their laser spectroscopic characteristics. We have demonstrated a simple physical method of Cr2+:ZnSe, ZnS and CdSe powder fabrication with average sizes below ~ 10μm and ~1μm (eliminating stage of bulk crystal growth) and demonstrated first ever mid-IR random lasing on these powders under optical excitation. In addition, we have examine suspensions and polymer films impregnated with Cr:II-VI powders for random lasing in the mid-IR. The powder, suspension and polymer samples are fabricated and characterized iii through the measurement of photoluminescence (PL) spectra, PL kinetics, and lasing threshold energy. 3) En route to low dimensional gain material, develop method for making laser active Cr, Co, and Fe doped ZnSe and ZnS quantum dots (QD), realize and study their laser spectroscopic characteristics. We have demonstrated a novel method of TM doped II-VI QDs fabrication based on laser ablation in liquid and Ar environment. TM doped II-VI QDs demonstrated strong mid-IR luminescence. And we also demonstrated the first mid-IR (2-3 μm) random lasing at room temperature of Cr2+:ZnS QD powders. The results obtained in this work open a new pathway for development of low-cost optically and electrically pumped broadly tunable mid-IR laser sources.
Kim, Changsu, "Optical, Laser Spectroscopic, and Electrical Characterization of Transion Metal Doped ZNSE and ZNS Nano-and-Microcrystals" (2009). All ETDs from UAB. 234.