Trap-assisted tunnelling and Shockley-Read-Hall lifetime of extended defects in In.53Ga.47As p+n junction

Several In.53Ga.47As p+n junctions with various extended defect densities (EDDs) have been grown by metalorganic vapor phase epitaxy (MOVPE), by carefully controlling the growth conditions. After fabrication, T-dependent J-V, C-V and double DLTS (DDLTS) are performed to extract the electrical field dependence of the extended defect levels. From this characterization, it is derived that the extended defects dominate the electrical field enhancement factor Gamma regardless of the value of the EDD and significantly increases the leakage current under reverse bias (i.e., decrease the Shockley-Read-Hall lifetime). These impacts are strongly connected to a "band-like" density of states of extended defects E2 at E-C-0.32 eV by comparing the DDLTS and T-dependent J-V characteristics. On the other hand, the reference sample (without EDs) surprisingly exhibits an even stronger field dependence with lower leakage current. Nevertheless, no straightforward candidate point defects can be found in this sample and the possible explanation are discussed

Low-frequency noise characterization of strained germanium pMOSFETs

Low-frequency noise in strained Ge epitaxial layers, which are grown on a reverse-graded relaxed SiGe buffer layer, has been evaluated for different front-end processing conditions. It has been shown that the 1/f noise in strong inversion is governed by trapping in the gate oxide (number fluctuations) and not affected by the presence of compressive strain in the channel. However, some impact has been found from the type of halo implantation used, whereby the lowest noise spectral density and the highest hole mobility are obtained by replacing the standard As halo by P implantation. At the same time, omitting the junction anneal results in poor device characteristics, which can be understood by considering the presence of a high density of nonannealed implantation damage in the channel and the gate stack near the source and the drain

Multicenter evaluation of signal enhancement algorithms for hearing aids

In the framework of the European HearCom project, promising signal enhancement algorithms were developed and evaluated for future use in hearing instruments. To assess the algorithms' performance, five of the algorithms were selected and implemented on a common real-time hardware/software platform. Four test centers in Belgium, The Netherlands, Germany, and Switzerland perceptually evaluated the algorithms. Listening tests were performed with large numbers of normal-hearing and hearing-impaired subjects. Three perceptual measures were used: speech reception threshold (SRT), listening effort scaling, and preference rating. Tests were carried out in two types of rooms. Speech was presented in multitalker babble arriving from one or three loudspeakers. In a pseudo-diffuse noise scenario, only one algorithm, the spatially preprocessed speech-distortion-weighted multi-channel Wiener filtering, provided a SRT improvement relative to the unprocessed condition. Despite the general lack of improvement in SRT, some algorithms were preferred over the unprocessed condition at all tested signal-to-noise ratios (SNRs). These effects were found across different subject groups and test sites. The listening effort scores were less consistent over test sites. For the algorithms that did not affect speech intelligibility, a reduction in listening effort was observed at 0 dB SNR. ©2010 Acoustical Society of Americ

Columbuskrabbetjes, <i>Planes minutus</i>, in onze kustwateren, tweede vondst voor de Noordzee

On 29th December 1982 two living specimens, a male and a female, of Planes minutus were found on a floating rope densely covered by stalked barnacles Lepas anatifera. The rope was taken by fishermen off the Belgian coast (approx. 51°15'N, 2°5O'E). This is only the second record of the species for the North Sea