Phototransistors in digital optical communications systems for 1?1.6 ?m wavelength

Receiver sensitivity comparable with that of a PIN-FET hybrid should be attainable using phototransistors at bit rates below 1 Gbit/s. However, significant improvement would call for a phototransistor having a very low input capacitance C and a high current gain hFE satisfying C<2×10?3?(hFE) pF, incorporated into an integrating receiver design.     

InGaAsP/InGaAs heterojunction p-i-n detectors with low dark current and small capacitance for 1.3?1.6 ?m fibre optic systems

A new long wavelength p-i-n photodetector, consisting of an In0.53 Ga0.47 As absorbing layer and an adjacent InGaAsP p-n junction is demonstrated. These diodes exhibit dark currents as low as 0.2 nA and a capacitance < 0.5 pF at ? 10 V for a device area of 1.3 × 10?4 cm2. The external quantum efficiency is ? 60% at ? = 1.3 ?m for front illumination. A systematic study of the background doping of the quaternary layers using different InP sources is also reported.     

4H-SiC MESFET肖特基栅接触的界面参数提取

研究了界面态对4H-SiC MESFET的肖特基栅接触的影响.栅接触工艺主要采用Ti/Pt/Au蒸发,经过剥离后形成.基于热电子理论提出了一种参数提取方法,得到界面态密度和界面电容分别为4.386×1013cm-2·eV-1和8.394×10-6F/cm2,这与测量得到的器件端特性一致.     

Stable monolithic GaAs FET oscillator

A monolithic X-band GaAs FET oscillator has been developed. Passive circuit components are lumped capacitors and inductors on semi-insulating GaAs; the chip size is 1.2 × 1.4 mm2. Stabilised with a Ba2Ti9O20 dielectric resonator, the oscillator delivers more than 30 mW output power at 10.8 GHz with a maximum chip efficiency of 20%. The frequency drift is better than 1 × 10?6/K from ?20°C to 80°C.     

New wideband high-gain stripline planar array for 12 GHz satellite TV

A new type of stripline planar array has been studied for 12 GHz satellite TV reception. A 16-element experimental antenna (dimensions?98×98×18 mm3), using a stripline corporate feed, presents a 2 : 1 VSWR bandwidth of over 2 GHz and a gain higher than 20.6 dBi in the 11.7?12.5 GHz bandwidth.     

New cut of quartz for SAW devices with extremely small temperature coefficient

A new cut of quartz for SAW devices was discovered by a leaky surface-wave mode. The temperature stability is extremely high and experimental temperature dependence of the phase delay change is within ±10 parts in 106 for the range from ?20 to 80°C. The propagation loss is only 2.6×10?4 dB/?.     

Measurement of radiative and auger recombination rates in p-type InGaAsP diode lasers

Carrier lifetimes and spontaneous emission rates are reported for InGaAsP diode lasers. For active layers Zn-doped in the range 1?2 × 1018/cm3 the radiative recombination constant B is 0.8 × 10?10 cm3/s and the nonradiative constant C is 0.9 × 10?28 cm6/s for a Cnp2 Auger process. For lightly doped lasers the Auger model alone cannot explain the data.     

Electron detachment in oxygen

A new experimental method for determining electron detachment (?) coefficients in swarm conditions in gases is described. Data are given for oxygen at pressures of 20 and 40torr (E/p=40?50 V cm?1 torr?1). ?/p varies from 2×10?3 to about 1.3×10?2cm?1torr?1.     

Temperature dependence of the Kerr effect in a silica optical fibre

The temperature dependence of the electro-optic Kerr effect has been measured in a silica-cored monomode optical fibre. The Kerr constant was measured as 5.3×10?16 mV?2 at 23°C with a temperature coefficient of +0.56% per deg C over the range 23 to 88°C. This measurement has implications for optical-fibre temperature and electric field sensors.     

Noise and responsivity of commercial p+n Ge avalanche photodiodes

Commercial p+n Ge APD samples from two manufacturers are shown to have comparable noise and responsivity, characterised by a quantum efficiency at 1.3 ?m wavelength of 0.7?0.75, and a bulk leakage current density at 20 C of 2?3×10?4 A cm?2 before avalanche multiplication. Surface uniformity of avalanche gain is much better than on earlier n+p devices of the same diameter (100 ?m).     

Reproducible low-resistivity AuMn ohmic contact for p-type GaAs

A novel ohmic contact 96% Au-4% Mn has been established for p-type GaAs. A specific contact resistivity of 2 × 10?7 ?cm2 has been obtained on 2 × 1019 cm?3 epitaxial layers after alloying, and a resistivity of 2 × 10?6 ?cm2 has been obtained on 2 × 1020 cm?3 doped layers without alloying. The contact is stable and reproducible.     

超二代像增强器分辨力随输入照度变化研究

为研究超二代像增强器在不同输入照度下的分辨力变化规律,在不同照度下分别对不同极限分辨力、信噪比以及等效背景照度像增强器的分辨力进行了测试.通过测试数据的分析,得出了极限分辨力、信噪比及等效背景照度在不同照度下对分辨力影响的规律.该规律表明,在5×10-2 lx～5×10-3 lx照度区间,不同性能参数像增强器的分辨力均...     

P-N结中的一个新电容模型——光生电荷的常分布电容(英文)

This paper initially suggests a new capacitance model, i.e., the constant distribution capacitance of photogenerated charge (C.D.C.P.C.). The capacitance originating from the distribution of photogenerated charge in a junction region does not connect with alternative electric signals applied on the junction. It essentially distinguishes from the depletion and diffusion differential capacitances as previously known. Since the photo-generated charge, Q, and the photogenerated voltage, V, are connected by the equation, Q-CV, where C is just the C.D.C.P.C. the importance of this new capacitance model is self-evident. In the paper, the expressions of C.D.C.P.C. under the condition of approximately abrupt and graded junctions are deduced respectively at low forward bias. As the examination of the validity of the C.D.C.P.C. model, the deduced results are applied to the contactless test method of the device leakage and a good agreement between the theoretic calculation and experimental results is obtained, which enables the quantitative determination of the device leakage by the high frequency photoconductor decay method to be possible,     

Thermodisplacement imaging of current in thin-film circuits

We present initial results on a novel scheme for measuring current distribution in thin-film circuits. When an AC current passes through a thin-film circuit, the resulting periodic heating sets up a dynamic surface displacement which can be detected using a phase-sensitive laser probe. Results indicate that the present system has a sensitivity of 4 × 10?3 ? for displacement and 2.7 × 10?2°C for temperature in a 1 Hz bandwidth. The spatial resolution can be as small as an optical wavelength and is currently limited to 2 ?m by the optics used. As the surface displacement amplitude depends on the thermal properties of the substrate material, the technique can also be used to detect defects beneath the metallisation in integrated-circuit structures.     

Spectral response of a point-contact diode in the submillimetre range

The spectral response of a fast GaAs point-contact diode in the millimetre- and submillimetre-wavelength range is described. N.E.P.s of 10-7W at 337 ?m and 4×10-6W at 98 ?m were obtained. The experimental and theoretical spectral responses for the diode are compared.     

Platinum intermetallic resistors for GaAs-based circuits

A simple technique for making intermetallic resistors of sheet resistance around 25 ?/? is described. The resistors were formed by reacting a 300 ? film of platinum with underlying GaAs to completion. PtGa, PtGa2 and PtAs2 phases were identified in the temperature range of 450°C to 550°C investigated. The temperature coefficient of resistivity was of the order of +9.2×10?4°C?1 at 25°C and the resistors appeared to be stable up to current densities of 105 A/cm2.     

InGaAs enhancement-mode MISFETs using double-layer gate insulator

In this letter we describe the fabrication of enhancement-mode MISFETs on InGaAs grown by liquid-phase epitaxy (LPE) using an anodic Al2O3/anodic native oxide double layer as a gate insulator. The normally-off device of 10 ?m gate length shows the effective channel mobility of 1400 cm2/Vs. The interface state density distribution of this double-layer MIS of InGaAs is also reported. The density of 2 × 1013 cm?2 eV?1 at Ec ?0.057 eV and the minimum of 8 × 1011 cm?2 eV?1 near midgap are measured from C/V characteristics.     

Low noise charge-sensitive preamplifier for fast pulse counting

A charge-sensitive pulse pre-amplifier is described, with the following characteristics: linear response of 1.04 × 1015 mV C?1 between 10?15 and 10?12 C, input noise ? 660 r.m.s. electrons, pulse repetition rate ? 3 × 106 pps, and rugged design.     

MOS Integrated Circuit Reliability

This paper presents information on the reliability of MOS integrated circuits based on p-channel enhancement-mode transistors, and describes their failure modes and mechanisms. The principal failure mechanisms were ion migration at the surface and oxide shorting. The results of experimental studies of the effects of variations in construction, processing, and levels of stress are presented, and are compared with other available information on MOS integrated circuit reliability. The failure rate for commercially available complex MOS arrays is on the order of 0.001 to 0.01 per 1000 h of operating life at 125°C for arrays containing approximately 600 p-channel transistors. This corresponds to a failure rate on the order of 5 × 10?6 to 5 × 10?5 per equivalent gate per 1000 h. The effects of device complexity, operating temperature, and other factors are discussed. A reliability prediction equation for MOS integrated circuits is derived from available information. An overall activation energy for functional failure mechanisms of approximately 5 kcal/mole (?0.2 eV/molecule) is considered applicable to typical MOS integrated circuits. Thus, the failure rate of MOS devices operated at 50°C ambient temperature can be predicted to be on the order of 10?6 to 10?5 per equivalent gate per 1000 h.     

1.55 ?m InGaAsP low-threshold buried-crescent injection laser

Fabrication of 1.55 ?m InGaAsP buried-crescent (BC) injection lasers with a p-n-p-n blocking structure is described. The BC lasers exhibit a threshold current as low as 14 mA at 25°C, very high yield, output power more than 10 mW and high-temperature operation up to 80°C. These BC lasers have continued to operate in stable CW mode at 50°C for more than 1000 h. The lifetime of the 1.55 ?m InGaAsP lasers at 50°C is estimated to exceed about 2.5 × 104 h.