Electron traps in thin layers of low-temperature-grown gallium arsenide with As-Sb nanoclusters

Electron traps in low-temperature-grown ～40-nm-thick GaAs layers containing nanometer As-Sb clusters have been studied using deep-level transient spectroscopy. Measurements at various bias voltages and small-amplitude filling pulses have allowed the identification of two groups (T1 and T2) of traps with substantially different thermal electron emission rates. It is shown that the density of traps T2 (with an activation energy of 0.56 ± 0.04 eV and electron capture cross section of 2 × 10^?13?10^?12cm²) is ～2 × 10¹²cm_?2, while the density of traps T1 (0.44 ± 0.02 eV and 2 × 10^?14?10^?13 cm², respectively) is ten times lower. It is assumed that, according to the existence of the two cluster groups observed in the layers under study, traps T2 are associated with clusters 4–7 nm in diameter and traps T1, with clusters up to ～20 nm in diameter.     

Matching degradation of threshold voltage and gate voltage of NMOSFET after Hot Carrier Injection stress

Device degradation modelling is more and more important for reliable circuit design. On MOSFET, the threshold voltage drift in time can lead to circuit performance degradation. In this study, V_T shift due to Hot Carrier Injection stress is accelerated on small width devices. V_T matching is also degraded during stress as a function of V_T deterioration. This width dependence allows explaining gate voltage matching behavior in the sub-threshold area used in low power analog applications.     

Effect of local structural defects on the precipitation of as in the vicinity of InAs quantum dots in a GaAs matrix

Electron-microscopy studies of GaAs structures grown by the method of molecular-beam epitaxy and containing arrays of semiconductor InAs quantum dots and metallic As quantum dots are performed. An array of InAs quantum dots is formed using the Stranski-Krastanow mechanism and consists of five layers of vertically conjugated quantum dots divided by a 5-nm-thick GaAs spacer layer. The array of As quantum dots is formed in an As-enriched GaAs layer grown at a low temperature above an array of InAs quantum dots using postgrowth annealing at temperatures of 400–600°C for 15 min. It is found that, during the course of structure growth near the InAs quantum dots, misfit defects are formed; these defects are represented by 60° or edge dislocations located in the heterointerface plane of the semiconductor quantum dots and penetrating to the surface through a layer of “low-temperature” GaAs. The presence of such structural defects leads to the formation of As quantum dots in the vicinity of the middle of the InAs conjugated quantum dots beyond the layer of “low-temperature” GaAs.     

Design of a novel MRI compatible manipulator for image guided prostate interventions

This paper reports a novel remotely actuated manipulator for access to prostate tissue under magnetic resonance imaging guidance (APT-MRI) device, designed for use in a standard high-field MRI scanner. The device provides three-dimensional MRI guided needle placement with millimeter accuracy under physician control. Procedures enabled by this device include MRI guided needle biopsy, fiducial marker placements, and therapy delivery. Its compact size allows for use in both standard cylindrical and open configuration MRI scanners. Preliminary in vivo canine experiments and first clinical trials are reported.     

使用BUS端口保护阵列实现有源ESD保护

许多便携式应用需要超过8kV的ESD保护,同时将电容保持在5pF以下。Z二极管能够单独满足这一要求,但当与开关或结型二极管等低电容PN二极管相结合时,它们可同时满足该应用的以下两种要求:低电容,以及高ESD和     

Mechanisms of InGaAlAs solid solution decomposition stimulated by InAs quantum dots

Mechanisms of InGaAlAs solid solution decomposition stimulated by a purposely deposited layer of InAs quantum dots are studied. Decomposition of the solid solution results in an increase in the effective quantum dot size and the shift of the photoluminescence line to as far as 1.3 μm. When aluminum atoms are added to the solid solution, the effect of In atom “conservation” within the dots is observed, which also causes an increase in the effective dot size. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 34, No. 3, 2000, pp. 330–333. Original Russian Text Copyright ? 2000 by Tsatsul’nikov, Volovik, Bedarev, Zhukov, Kovsh, Ledentsov, Maksimov, Maleev, Musikhin, Ustinov, Bert, Kop’ev, Bimberg, Alferov.