BILOW-simulation of low-temperature bipolar device behavior

The BILOW simulation program for investigating bipolar transistor behavior in the temperature range 77-300 K is discussed. Differences between the numerical approaches required for simulation of low-temperature behavior compared to room-temperature simulation are presented. Efficient numerical models for the physical parameters in the carrier transport equations and Poisson's equation for the temperature range of 77-300 K, including a new highly accurate numerical model for the temperature and doping concentration dependence of carrier mobility, are discussed. A temperature- and doping-concentration-dependent model for apparent bandgap narrowing is also discussed. The internal characteristics of a typical bipolar transistor are simulated over the 300-77 K range. The behavior of current gain β and the unity gain frequency f_T versus collector current density for different temperatures are calculated and discussed     

硅低温双极晶体管的数值模拟

本文讨论了有关低温双极器件模拟物理参数的低温模型和各种低温物理效应,确立了适用于低温双极器件模拟的数值分析方法,建立了适用于77-300K温度范围内硅双极器件模拟程序,最后模拟分析了一典型结构品体管的常温和低温时的工作特性。     

4K超高清节目制作中的问题与解决方法

广东广播电视台从2018年4K频道开播以来,在节目制作和4K技术具体应用过程中积累了一些经验。因此,结合4K节目制作过程中遇到的问题,重点探讨具体的解决方案,供同行参考。     

Cryogenic Parametric Amplifier Noise Performance at 4.2 K

Results of an experiment in which a 4.5- -5.0-GHZ paramp was operated at 4.2 K are reported. The measured noise temperature at 4.2 Kwas 12 K. This is 6 K lower than the unit's noise temperature at its normal operating point of 18 K. It is concluded that varactor heating by the pump oscillators limited the improvement in noise performance. Prospects for further improvements in paramp noise temperature using better varactors are discussed.     

0.3K下的GaAs/Al_xGa_(1-x)As异质结中的分数量子霍耳效应

本文从实验上比较了低浓度 GaAs/Al_xGa_(1-x)As异质结样品在4.2K、1.3K和0.34K 温度下的整数量子霍耳效应,报道了填充因子v=2/3的分数量子霍耳效应的实验观察结果.讨论了低浓度GaAs/Al_xGa_(1-x)As样品中宏观不均匀性对实验结果的影响.     

在声系统分频器中电容器的比较

讨论了电容器影响音质的客观测量参数及听觉试验方法,对主观听音的评价结果进行了统计分析.特别讨论了K73-16电容器的表现.最后给出了电容器的主观音质评价与结论.希望对广大音箱设计者选用分频器电容有较大的参考作用.     

A selectively contacted dual-channel HEMT

A dual-channel high-electron-mobility transistor (HEMT) with selective contacts to each channel is discussed. The conduction properties of each individual channel are obtained using simple DC measurements. Isolation between the channels and the presence of the kink effect are discussed. In addition, inverter-like behavior from a single device is obtained at 77 K     

离子交换玻璃波导的模型分析

对采用BK7玻璃并经过K+ Na+ 二次离子交换法制备的波导 ,用数值求解分析了一次和二次离子交换所形成的折射率分布 ,并分析了影响折射率变化的原因。     

Free carrier optical absorption at 10.6 μm in GaAs

Optical absorption measurements at 10.6 μm have been perfor-med in chromium doped GaAs samples using a calorimetric tech-nique at 300 K, and an optical system to determine the varia-tion of the absorption versus temperature between 300 K and 650 K. Hall effect measurements have also been carried out in the same temperature range. The optical absorption cross sec-tion for both electrons and holes are discussed and experi-mentally determined. A semi-empirical formula is deduced which permit the calculation of the 10.6 μm free carrier absorption at any temperature and doping level provided the electron mobility is known. Besides free carrier and multi-phonon absorption another mechanism must be considered to explain the experimental data. Possible effect of small pre-cipitates is discussed.     

The sensible superconductor [magnesium diboride]

Cheap to make, simple to cool, easy to shape into wires, magnesium diboride could throw the field of superconducting applications wide open. With a superconducting transition temperature of 39 K, it can be conveniently cooled with commercial cryocoolers or liquid hydrogen (boiling point: 20.2 K). A powder that can be found in any well-stocked chemistry laboratory, it had never been tested for superconductivity until very recently. However, just 18 months after its discovery, magnesium diboride is on the road to producing real-world applications. The main properties of the material and the fabrication of superconducting wires are discussed in this article. Its advantages over high-temperature superconductors are discussed     

Performance of GaAs MESFET's at Low Temperatures (Short Papers)

The noise- and s-parameters of a GaAs MESFET with 1-mu m gate Iength are characterized versus temperature. At room temperature, the noise figure measured at 12 GHz is 3.5 dB. At 90 K, the noise figure decreases to 0.8 dB (T/sub e/ = 60 K). The associated gain is 8 dB. The design of a cooled amplifier for the 11.7-12.2-GHz communication band is discussed. At 60 K, the three-stage amplifier exhibits 1.6-dB noise figure (T/sub e/ = 130 K) and 31-dB gain.     

Thermoelectric Properties of InSb Nanowires Over a Wide Temperature Range

The thermoelectric power and electrical conductance of bundles of indium antimonide nanowires with a diameter of about 5 nm have been measured over the temperature range of 80 K to 400 K. In the range from 80 K to 300 K, the temperature dependence of the conductance of nanowires is close to power law, while the thermopower increases linearly with temperature. The thermoelectric properties of the nanowires are discussed in terms of the Luttinger liquid theory, taking into account enhancement of the electron–electron interaction in one-dimensional conductors.     

Coupling coefficient calculations for lead-tin telluride distributed feedback lasers

Coupling coefficient calculations of the type originally published for gallium arsenide distributed feedback (DFB) lasers are here extended to the lead-tin telluride based family of devices. Specific calculations of the coupling coefficient as a function of active region and grating dimensions are presented for PbTe/Pb1-xSnxTe/PbTe devices,x = 0.13andx = 0.18, at 8 K and 77 K, and the implications of the results for device design and fabrication are discussed.     

The flip-chip InGaAsSb/GaSb LEDs emitting at a wavelength of 1.94 μm

Spectral, current-voltage, and light-current characteristics of light-emitting diodes (LEDs) with an InGaAsSb active layer (the emission wavelength is 1.94 μm at 300 K) are studied in the temperature range of 77–543 K. The LEDs were fabricated by liquid-phase epitaxy on the GaSb substrate and had a flip-chip structure. Spectral and emission-power characteristics are discussed in relation to specific features of the structure, emission absorption in the substrate, and Joule heating.     

Metal clad Pb1-xSnx Se/Pb1-x-yEuy SnxSe distributed feedback lasers

Distributed-feedback Pb_1-xSn_xSe double heterostructure stripe geometry diode lasers fabricated using molecular-beam epitaxy are discussed. These lasers operate in the CW mode up to 90 K and in the pulse mode up to 100 K. They are unique in their low tuning rate with injection current 4 cm^-1/A, and in that they withstand high CW injection currents without damage. These features are probably the result of the metal cladding layer located on top of the gratings     

High-Tc superconductivity seeks a digital home

Two obvious applications of high-T_c superconductors are discussed: the use of Josephson technology at 77 K and the use of high-T_c lines for interconnects. The difficulties that must be addressed for each of these is discussed, and the prospects for overcoming them are assessed. The need to achieve full compatibility with polymers is stressed     

Investigation of temperature-dependent small-signal performances of TB SOI MOSFETs

This paper investigated the temperature dependence of the cryogenic small-signal ac performances of multi-finger partially depleted (PD) silicon-on-insulator (SOI) metal oxide semiconductor field effect transistors (MOSFETs), with T-gate body contact (TB) structure. The measurement results show that the cut-off frequency increases from 78 GHz at 300 K to 120 GHz at 77 K and the maximum oscillation frequency increases from 54 GHz at 300 K to 80 GHz at 77 K, and these are mainly due to the effect of negative temperature dependence of threshold voltage and transconductance. By using a simple equivalent circuit model, the temperature-dependent small-signal parameters are discussed in detail. The understanding of cryogenic small-signal performance is beneficial to develop the PD SOI MOSFETs integrated circuits for ultra-low temperature applications.     

Optical remote sensing of aircraft emissions with the K300

The K300 double pendulum interferometer, a compact high-resolution Fourier transform spectrometer designed for outdoor optical remote sensing in the infrared spectral region, is described. The remote diagnostic of hot aircraft engine emissions is a very interesting application of the infrared spectroscopy. First results of such measurements performed with the Kayser-Threde double pendulum interferometer K300 at the DLR airport, Oberpfaffenhofen, on 15 January 1992, are discussed     

In0.25Ga0.75As/AlAs-based resonant tunnelingdiodes grown on prepatterned and nonpatterned GaAs (100) substrates

The DC current-voltage characteristics of strained In_0.25 Ga_0.75As/AlAs resonant tunneling diode (RTD) structures grown on GaAs (100) substrates which also include prepatterned mesas are discussed. The observed peak-to-valley current ratios (PVRs) of 4.5 at 300 K and 15 to 77 K with corresponding peak current densities of 11 and 13 kA/cm² are the highest values of PVR to date for this strained system and are the same for the nonpatterned and prepatterned regions     

Low-noise single-photon detection at wavelength 1.55 μm

The photon-counting performance of commercially available InGaAs/InP avalanche photodiodes operated in Geiger mode was investigated at temperatures between 77 and 260 K. In particular, their noise equivalent power was measured to be 4×10^-17 WHz ^-1/2 at 77 K. The implications of these results in the context of a quantum cryptography application are discussed