Fabrication of transition metal selenides and their applications in energy storage

Recent progress in research on InGaAlN and II–VI systems has been remarkable, and this paper reviews the properties of these materials from the viewpoint of making reliable light-emitting devices. The growth of these materials by molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) is also reviewed, and the current status of both materials is reviewed with respect to light-emitting devices.

InGaAlN and II–VI Systems for Blue–Green Light-Emitting Devices†

Transmission electron microscopy (TEM) investigations of metal organic vapor phase deposition grown AlxGa1−xN/GaN heterostructures on Si(111) containing an AlN high-temperature buffer layer have been carried out. The structural properties at the interface and in the epilayer as well as the electronic properties suitable for a high electron mobility transistor (HEMT) were analyzed and compared with systems grown on Al2O3(0001). High resolution TEM (HRTEM) at the AlN/Si(111) interface reveals a 1.5–2.7 nm thick amorphous SiNx layer due to the high growth temperature of TAlN=1040 °C. Therefore, a grain-like GaN/AlN region extending 40–60 nm appears and it is subsequently overgrown with (0001) orientated GaN material because of geometrical selection. The residual strain at the AlN/Si(111) interface is estimated to be er=0.3±0.6% by Fourier filtering of HRTEM images and a moire fringe analysis. This indicates almost complete relaxation of the large mismatch f(AlN/Si)=+23.4% which seems to be supported by the S...

Structural properties of AlGaN/GaN heterostructures on Si(111) substrates suitable for high-electron mobility transistors

We investigate Cu(In,Ga)Se 2 -based solar cells with a new ZnSe buffer layer deposited by metal-organic vapour deposition and compare their electronic properties to reference cells using a standard CdS buffer layer. The best solar cell with a ZnSe buffer layer achieves an efficiency of 11.6%. We further investigate a large series of solar cells with varied thickness of both types of buffer layers by means of quantum efficiency measurements in equilibrium and under light and voltage bias. The characterization of the devices concentrates on the analysis of the collection of photogenerated holes from the buffer layer. We introduce a new method to determine the recombination probability of holes at the buffer/absorber interface. We find a similar interface recombination probability of about 40% for both devices, those with a ZnSe buffer layer and those with a CdS buffer layer. An anomalous enhancement of the quantum efficiency measured under current bias is ascribed to a barrier modulation effect which is caused by light absorbed in the buffer layer.

Cu(In,Ga)Se2 solar cells with a ZnSe buffer layer: interface characterization by quantum efficiency measurements

Photoluminescence study of radiative transitions in ZnTe bulk crystals

Luminescence caused by extended lattice defects in epitaxially grown ZnTe layers

Photoassisted growth and nitrogen doping of ZnSe

The properties of ZnSe-based heterostructures on (001) GaAs substrates grown by metalorganic vapor phase epitaxy (MOVPE) are compared with those grown by molecular beam epitaxy (MBE). The structural and optical properties are examined with high-resolution X-ray diffraction (HRXRD) and photoluminescence (PL). Furthermore the results of C–V measurements of p-ZnSe layers doped with nitrogen are discussed and I–V characteristics and electroluminescence (EL) spectra of LEDs grown with both techniques are presented. ZnSe/Zn(SSe) MQWs are prepared with MOVPE and (ZnCd)Se/ZnSe MQWs with MBE to improve the optical efficiency of the diodes.

M. Kastner

Papers

Luminescence caused by extended lattice defects in epitaxially grown ZnTe layers

Photoassisted growth and nitrogen doping of ZnSe

ZnSe‐Based MOVPE and MBE Grown LEDs

Critical Thickness Determination of II-VI Semiconductors by Rheed and X-Ray Diffraction

Metalorganic chemical vapor deposition of ZnSe films on glass and GaAs(111) substrates