Milos Nesladek

Observation of the subgap optical absorption in polymer-fullerene blend solar cells

This letter reports on highly sensitive optical absorption measurements on organic donor-acceptor solar cells, using Fourier-transform photocurrent spectroscopy (FTPS). The spectra cover an unprecedented dynamic range of eight to nine orders of magnitude making it possible to detect defect and disorder related sub-band gap transitions. Direct measurements on fully encapsulated solar cells with an active layer of poly[2-methoxy-5-(3′,7′-dimethyl-octyloxy)]-p-phenylene-vinylene:(6,6)-phenyl-C61-butyric-acid (1:4 weight ratio) enabled a study of the intrinsic defect generation due to UV illumination. Solar cell temperature annealing effects in poly(3-hexylthiophene):PCBM (1:2 weight ratio) cells and the induced morphological changes are related to the changes in the absorption spectrum, as determined with FTPS.

High‐Performance Broadband Photodetector Using Solution‐Processible PbSe–TiO2–Graphene Hybrids

Highly sensitive, multicomponent broadband photodetector devices are made from PbSe/graphene/TiO(2). TiO(2) and PbSe nanoparticles act as light harvesting photoactive materials from the UV to IR regions of the electromagnetic spectrum, while the graphene acts as a charge collector for both photogenerated holes and electrons under an applied electric field.

Surface acoustic wave propagation in aluminum nitride-unpolished freestanding diamond structures

High-quality surface acoustic wave (SAW) filters based on aluminum nitride (AlN)/diamond layered structures were prepared using the nucleation side of polycrystalline chemical vapor deposition (CVD) diamond, removed from a silicon substrate by wet etching. Highly oriented AlN thin films with optimized piezoelectric properties and with various thicknesses were sputtered onto the nucleation side of freestanding diamond. The effect of AlN thickness on the SAW phase velocity, the coupling coefficient, and the device characteristics were investigated. Experimental results show that the Rayleigh wave and the higher modes are generated. These results agree well with calculated dispersion curves and demonstrate that a high electromechanical coupling coefficient together with a high phase velocity can be obtained by using the nucleation side of freestanding CVD diamond layer.

Adhesion of diamond coatings on cemented carbides

WTCM,B-3590 DIEPENBEEK,BELGIUM.Nesladek, M, LIMBURGS UNIV CENTRUM,INST MAT RES,DIV MAT PHYS,CAMPUSLAAN 1,B-3590 DIEPENBEEK,BELGIUM.

Physics and applications of CVD diamond

Marshall Stoneham: Thinking about diamond Olivier Williams, Milos Nesladek: Growth and properties of nanocrystalline diamond Films Tokuyuki Teraji: Chemical Vapor Deposition of Homoepitaxial Diamond Films Yutaka Anado, Atsuhito Sawabe: Heteroepitaxy of diamond C. E. Nebel, B. Rezek, D. Shin, H. Watanabe: Surface electronic properties of H-terminated diamond in contact with electrolytes Shin, B. Rezek, C.E. Nebel: Photo- and electrochemical bonding of DNA to single crystalline CVD diamond Vincent Mortet, Ken Haenen, Oliver Williams: Diamond: Acoustic wave filters and sensors applications Jonathan Goos: Defects and dopants in diamond Satoshi Koizumi, Mariko Suzuki, Julien Pernot: n-Type doping of diamond: growth, electrical transport and devices Jelezko, J. Wrachtrup: Single defect centers in diamond Hideyo Okushi, Hideyuki Watanabe, Satoshi Yamasaki, Shokichi Kanno: Emission properties from dense exciton gases in diamond Heinz Pernegger: High Mobility Diamonds and Particle Detectors Etienne Bustarret: Superconducting diamond

Conventional n-type doping in diamond: state of the art and recent progress

Recent progress in chemical vapour deposition (CVD) diamond technology has enabled the preparation of high-quality n-type CVD diamond layers using phosphorus as a dopant. CVD diamond can therefore be considered as a new interesting conventional wide-gap semiconducting material having both n- and p-type dopants, which makes it attractive for numerous applications in high-temperature, high-voltage and high-frequency devices. The concentration of phosphorus in n-type CVD diamond can be controlled in the concentration range of 1 × 1016–5 × 1019 cm−3 with a carrier mobility exceeding 600 cm2 V−1 s−1. In this review, the most relevant questions concerning the preparation of P-doped diamond are addressed and discussed in terms of future progress and novel electronic devices. We not only discuss the preparation of single crystal epitaxial diamond but also address the growth of large-area n-type polycrystalline CVD diamond, which can be useful for several applications such as for detectors or electron emitters.

Optical properties of microcrystalline materials

Note: IMT-NE Number: 269 Reference PV-LAB-ARTICLE-1998-012doi:10.1016/S0022-3093(98)00202-6 Record created on 2009-02-10, modified on 2017-05-10

Photochromism of vacancy-related centres in diamond

Optical experiments, involving photoluminescence (PL), the PL excitation and quenching spectra, as well as transmission and its quenching, were used to analyse the photochromic behaviour of some vacancy-related complexes in diamond. The 2.156 eV, 1.945 eV and 1.68 eV optical centres in CVD diamond are attributed to the neutral nitrogen-vacancy, negative nitrogen-vacancy and neutral silicon-vacancy ([Si-V]0 ) centres, respectively. Oscillatory behaviour in the excitation spectrum of the 1.68 eV luminescence is observed and from the threshold of the oscillations a position of EC - 2.05 eV is suggested for the ground state of the [Si-V]0 centre.

Superconductive B-doped nanocrystalline diamond thin films: Electrical transport and Raman spectra

Electrical transport properties of thin boron doped nanocrystalline diamond films with thicknesses of 60–500nm have been studied. The Raman spectra measured exhibit Fano resonances, characteristic for B concentrations close to the metal-to-insulator transition. Upon increasing the B concentration, the sp2 carbon related Raman resonances vanish. In such boron-doped nanocrystalline diamond films, a positive magnetoresistance could be observed at liquid helium temperatures. The boron doped diamond films show conductivity similar to that of B-doped epitaxial diamond without any significant contribution of the grain boundary transport, leading to the superconductive transition in nanocrystalline diamond at ∼1.66K.

High velocity SAW using aluminum nitride film on unpolished nucleation side of free-standing CVD diamond

High performances surface acoustic wave (SAW) filters based on aluminium nitride (AlN)/diamond layered structure have been fabricated. The C-axis oriented aluminum nitride films with various thicknesses were sputtered on unpolished nucleation side of free-standing polycrystalline chemical vapor deposition (CVD) diamond obtained by silicon substrate etching. Experimental results show that high order modes as well as Rayleigh waves are excited. Experimental results are in good agreement with the theoretical dispersion curves determined by software simulation with Greens function formalism. We demonstrate that high phase velocity first mode wave (so-called Sezawa wave) with high electromechanical coupling coefficient are obtained on AlN/diamond structure. This structure also has a low temperature coefficient of frequency (TCF), and preliminary results suggest that a zero TCF could be expected.