Inductively Coupled Plasma Etching in ICl- and IBr-Based Chemistries. Part II: InP, InSb, InGaP, and InGaAs

A parametric study of Inductively Coupled Plasma (ICP) etching of InP, InSb, InGaP, and InGaAs has been carried out in ICl/Ar and IBr/Ar chemistries. Etch rates in excess of 3.1 for InP, 3.6 for InSb, 2.3 for InGaP, and 2.2 m/min for InGaAs were obtained in IBr/Ar plasmas. The ICP etching of In-based materials showed a general tendency: The etch rates increased substantially with increasing ICP source power and rf chuck power in both chemistries, while they decreased with increasing chamber pressure. The IBr/Ar chemistry typically showed higher etch rates than ICl/Ar, but the etched surface morphologies were fairly poor for both chemistries.     

Small-signal characteristics of bottom-emitting intracavitycontacted VCSEL's

We characterize the small-signal frequency response of intracavity contacted ~970 nm VCSEL's designed for flip-chip bonding to electronic circuits and then modified with reduced capacitance and a novel lateral current injection method to obtain a high-speed response. We measure 3-dB bandwidths in excess of 10 GHz and an extracted K-factor limited f-max of 95 GHz for fabricated single-mode ~970-nm lasers     

Cosmological Applications of a Wavelet Analysis on the Sphere

The cosmic microwave background (CMB) is a relic radiation of the Big Bang and as such it contains a wealth of cosmological information. Statistical analyses of the CMB, in conjunction with other cosmological observables, represent some of the most powerful techniques available to cosmologists for placing strong constraints on the cosmological parameters that describe the origin, content and evolution of the Universe. The last decade has witnessed the introduction of wavelet analyses in cosmology and, in particular, their application to the CMB. We review here spherical wavelet analyses of the CMB that test the standard cosmological concordance model. The assumption that the temperature anisotropies of the CMB are a realisation of a statistically isotropic Gaussian random field on the sphere is questioned. Deviations from both statistical isotropy and Gaussianity are detected in the reviewed works, suggesting more exotic cosmological models may be required to explain our Universe. We also review spherical wavelet analyses that independently provide evidence for dark energy, an exotic component of our Universe of which we know very little currently. The effectiveness of accounting correctly for the geometry of the sphere in the wavelet analysis of full-sky CMB data is demonstrated by the highly significant detections of physical processes and effects that are made in these reviewed works.     

Suppression of drain source ringing in 100 kHz MOSFET induction heating power supply

The letter is concerned with a full bridge, current-fed MOSFET inverter feeding a parallel resonant induction heating load. A means of suppressing ringing between parasitic lead inductance and drain source capacitance is described.     

Comparative equilibration and online technique for determination of non-exchangeable hydrogen of keratins for use in animal migration studies

Stable hydrogen-isotope ratios (deltaD) of keratin provide a novel means for tracking geographical movements of birds and other species. Here we describe a rapid, low cost, analytical approach to facilitate online continuous-flow isotope-ratio mass spectrometry (CF-IRMS) deltaD analyses of keratins (120-160 samples per day) through the use of calibrated keratin working standards and "comparative equilibration" to correct for the effects of moisture on exchangeable hydrogen. It is anticipated that this analytical approach and CF-IRMS will greatly aid in providing cost effective and directly comparable deltaD results on keratins and feathers among various laboratories and researchers involved in animal migration studies.     

Carbon-doped base GaAs-AlGaAs HBT's grown by MOMBE and MOCVDregrowth

High-quality GaAs-AlGaAs heterojunction bipolar transistors (HBTs) in which the carbon-doped base layers (p=10¹⁰-10²⁰ cm^-3, 400-800 Å thick) and Sn-doped collector and subcollector layers are grown by metalorganic molecular-beam epitaxy (MOMBE) and a subsequent regrowth using metalorganic chemical vapor deposition (MOCVD) is used to provide the n⁺ AlGaAs emitter and GaAs/InGaAs contact layers are discussed. A current gain of 20 was obtained for a base doping of 10¹⁹ cm^-3 (800 Å thick) in a 90-μm-diameter device, with ideality factors of 1.0 and 1.4 for the base-collector and emitter-base junctions, respectively, demonstrating the excellent regrowth-interface quality. For a base doping of 10²⁰ cm^-3 (400 Å thick), the current gain decreased to 8     

Highpower switching of multielectrode broad area lasers

24 ps optical pulses of peak power in excess of 1.3 watts are continuously generated at GHz repetition rates using a GaAs/AlGaAs single quantum well broad area laser with an intracavity loss modulator. Efficient high power light modulation is also demonstrated with the same structure.<>     

Class E switching-mode power amplifier for high-frequency electric process heating applications

The letter is concerned with the application of a class E convertor to electric process heating. A simple efficient convertor is described which is suitable for high-frequency electric process heating loads.     

Comments on `New measurement method of Gunn-diode impedance?

A discussion is given of processes which affect the estimation of the conductance/voltage relationships of transferred-electron oscillators from the start of oscillation conditions. It is concluded that the technique is likely to be unreliable, except in broad qualitative terms.