Post-growth modification of electrical properties of ZnTe nanowires

ZnTe nanowires, grown by a vapor-liquid-solid technique are p-type and show a very high intrinsic resistivity. Enhancement of the nanowire conductivity was investigated by vacuum annealing, doping and Joule heating. The current-voltage (I-V) characteristics were measured in all cases and electrical parameters such as resistivity, carrier concentration and mobility were computed from the I-V curves. An improvement of five orders of magnitude in the electrical conductivity was seen after thermal annealing and Joule heating, comparable to the enhancement in conductivity obtained by doping. Published by Elsevier B.V.X1167sciescopu

Bandgap engineering of CdxZn1-xTe nanowires

Bandgap engineering of single-crystalline alloy CdxZn1-xTe (0 <= x <= 1) nanowires is achieved successfully through control of growth temperature and a two zone source system in a vapor-liquid-solid process. Extensive characterization using electron microscopy, Raman spectroscopy and photoluminescence shows highly crystalline alloy nanowires with precise tuning of the bandgap. It is well known that bulk CdxZn1-xTe is popular for construction of radiation detectors and availability of a nanowire form of this material would help to improve detection sensitivity and miniaturization. This is a step forward towards the accomplishment of tunable and predetermined bandgap emissions for various applications.open1133sciescopu

Synthesis and characterization of carbon nanowalls on different substrates by radio frequency plasma enhanced chemical vapor deposition

A radio frequency plasma enhanced chemical vapor deposition system was used for the successful growth of thin vertical carbon nanowalls, also known as vertical graphene, on various substrates. Transmission electron microscopy studies confirmed the presence of vertical graphene walls, which are tapered, typically consisting of 10 layers at the base tapering off to 2 or 3 layers at the top. The sides of the walls are facetted at quantized angles of 30 and the facetted sides are usually seamless. Growth occurs at the top open edge which is not facetted. Hydrogen induced etching allows for nucleation of branch walls apparently involving a carbon onion-like structure at the root base. Characterization by a superconducting quantum interference device showed magnetic hysteresis loops and weak ferromagnetic responses from the samples at room temperature and below. Temperature dependence of the magnetization revealed a magnetic phase transition around T = 50 K highlighting the coexistence of antiferromagnetic interactions as well as ferromagnetic order.147491sciescopu