Electrical and Optical Properties of Indium and Lead Co-Doped Cd0.9Zn0.1Te

We have investigated the electrical and optical properties of Cd0.9Zn0.1Te:(In,Pb) wafers obtained from the tip, middle, and tail of the same ingot grown by modified vertical Bridgman method using I-V measurement, Hall measurement, IR Transmittance, IR Microscopy and Photoluminescence (PL) spectroscopy. I-V results show that the resistivity of the tip, middle, and tail wafers are 1.8 × 1010, 1.21 × 109, and 1.2 × 1010 Ω·cm, respectively, reflecting native deep level defects dominating in tip and tail wafers for high resistivity compared to the middle part. Hall measurement shows the conductivity type changes from n at the tip to p at the tail in the growth direction. IR Transmittance for tail, middle, and tip is about 58.3%, 55.5%, and 54.1%, respectively. IR microscopy shows the density of Te/inclusions at tip, middle, and tail are 1 × 103, 6 × 102 and 15 × 103/cm2 respectively. Photoluminescence (PL) spectra reflect that neutral acceptor exciton (A0,X) and neutral donor exciton (D0,X) of tip and tail wafers have high intensity corresponding to their high resistivity compared to the middle wafer, which has resistivity a little lower. These types of materials have a large number of applications in radiation detection.

ZnO Nanorod/Graphene Hybrid-Structures Formed on Cu Sheet by Self-Catalyzed Vapor-Phase Transport Synthesis

High crystalline ZnO nanorods (NRs) on Zn pre-deposited graphene/Cu sheet without graphene transfer process have been fabricated by self-catalyzed vapor-phase transport synthesis. Here, the pre-deposited Zn metal on graphene not only serves as a seed to grow the ZnO NRs, but also passivates the graphene underneath. The temperature-dependent photoluminescence spectra of the fabricated ZnO NRs reveal a dominant peak of 3.88 eV at 10 K associated with the neutral-donor bound exciton, while the redshifted peak by bandgap shrinkage with temperature and electron-lattice interactions leads a strong emission at 382 nm at room temperature. The optical absorption of the ZnO NRs/graphene hetero-nanostructure at this ultraviolet (UV) emission is then theoretically analyzed to quantify the absorption amount depending on the ZnO NR distribution. By simply covering the ZnO NR/graphene/Cu structure with the graphene/glass as a top electrode, it is observed that the current-voltage characteristic of the ZnO NR/graphene hetero-nanojunction device exhibits a photocurrent of 1.03 mA at 3 V under a light illumination of 100 μW/cm2. In particular, the suggested graphene/ZnO NRs/graphene hybrid-nanostructure-based devices reveal comparable photocurrents at a bidirectional bias, which can be a promising platform to integrate 1D and 2D nanomaterials without complex patterning process for UV device applications.

The role of neutral donor ligands in the isoselective ring-opening polymerization of rac-β-butyrolactone

Simple achiral neutral donor ligands modify catalyst structure and function to enable access to isoenriched poly-3-hydroxybutyrate, a biodegradable material with properties similar to isotactic polypropylene.

From lithium to sodium: design of heterometallic molecular precursors for the NaMO2 cathode materials

Based on the Li2M2L6 model structure, an addition of extra neutral donor ligand enables the formation of Na2M2L6(THF)2 molecular precursors for the NaMO2 oxide cathode materials.