Bipolar transistor fabrication in low-temperature (745°C) ultra-low-pressure chemical-vapor-deposited epitaxial silicon

In this letter we report for the first time the successful fabrication of bipolar transistors in low-temperature (Tdep= 745°C) epitaxial silicon deposited by a chemical-vapor-deposition (CVD) technology. The epitaxial layers were deposited by an ultra-low-pressure CVD (U-LPCVD) technique utilizing an optimized in-situ predeposition argon sputter clean. The critical parameter during the sputter clean has been identified as the substrate bias. Bias voltages of -200 or -300 V create dislocations that form emitter-collector shunts during the bipolar transistor fabrication process; a bias voltage of -100 V, however, permits the deposition of essentially defect-free (<10 dislocations cm^-2by defect etching) epitaxial films suitable for bipolar transistor fabrication.     

High-power output over 200 mW of 1.3 µm GaInAsP VIPS lasers

Maximum CW output power was investigated in GaInAsP 1.3μm V-grooved inner stripe on P-substrate (VIPS) lasers considering both cavity length and facet reflectivity. Long-cavity lasers show a strong dependence of maximum output power on front reflectivity. A CW light output over 200 mW was obtained at room temperature using a 700 μm long cavity laser with 5 and 98 percent reflectivity of the front and rear facets, respectively. The fundamental transverse mode operation was confirmed up to 170 mW. A coupled power over 110 mW into a single-mode fiber was achieved with a coupling efficiency of 58 percent. We have verified the high reliability under high power levels, as high as 75 percent of the maximum CW output powers at room temperature.     

An X-band 22.5°/45° digital phase shifter based on switched filter networks

The design approach and performance of a 22.5°/45°digital phase shifter based on a switched filter network for X-band phased arrays are described. Both the MMIC phase shifters are fabricated employing a 0.25μm gate GaAs pHEMT process and share in the same chip size of 0.82×1.06 mm². The measurement results of the proposed phase shifters over the whole operating frequency range show that the phase shift error is less than 22.5°±2.5°, 45°±3.5°, which shows an excellent agreement with the simulated performance, the insertion loss is within the range of 0.9-1.2 dB for the 22.5°phase shifter and 0.9-1.4 dB for the 45°phase shifter, and the input/output return loss is better than -12.5 and -11 dB respectively. They also achieve the similar P_1dB continuous wave power handing capability of 24.8 dBm at 10 GHz. The phase shifters show a good phase shift error, insertion loss and return loss in the X-band (40%), which can be employed into the wide bandwidth multi-bit digital phase shifter.     

Laser-recrystallized silicon thin-film transistors on expansion-matched 800°C glass

Laser-recrystallized silicon thin-film transistors (TFT's) have been fabricated, for the first time, on a novel, potentially low-cost glass substrate, The 0.5-µm-thick silicon films were deposited along with appropiate dielectric layers on Corning Code 1729 glass substrates and recrystallized using an argon ion laser. The n-channel enhancement-mode transistors were made using conventional IC device fabrication procedures modified to have a maximum processing temperature of 800°C. Transistor's made in the recrystallized silicon show field-effect electron mobilities as high as 270 cm²/V.s, approximately 15 times that of comparable devices made in as-deposited polycrystalline-silicon films. The recrystallized silicon devices also exhibit lower threshold voltages and lower leakage currents than do comparable polycrystalline-silicon devices.     

Lateral confinement InGaAsP superluminescent diode at 1.3 µm

A superluminescent diode (SLD) has properties, based on the degree of coherence, that are bounded by those of the light emitting diode and the laser diode. The SLD can be designed to meet a wide range of optical system needs. By introducing ridge-waveguide lateral confinement, a good anti-reflection coating at one end and a high reflectivity mirror at the other, we have demonstrated an SLD that allows 30 percent coupling efficiency into a lensed 0.23 NA, 50 μm diameter graded index core fiber. The power in the fiber is 550 μW at 250 mA and 20°C. It is possible to maintain a constant power level in the fiber greater than 250 μW over the temperature range 0 to 35°C by adjusting the current. The spectral width is 300 Å and the modulation bandwidth 350 MHz. PCM with 400 Mbit/s rate has been observed. These devices are relatively easy to fabricate from ridge-waveguide lasers or any other lateral confinement laser.     

Record power characteristics of InGaAs/AlGaAs/GaAs heterostructure lasers

Continuous-wave output powers of 9.2 W at a constant heatsink temperature of 10°C and 12.2 W at a stabilized temperature of the active region have been obtained on an InGaAs/AlGaAs laser with a 0.4-μm-thick waveguide, operating at 1.03 μm. Record-breaking output mirror power densities of, respectively, 29.9 and 40 MW/cm² have been achieved without catastrophic optical mirror damage in the two temperature-stabilization regimes. A maximum power conversion efficiency of 66% has been achieved in a laser with a cavity length of 2 mm. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 35, No. 3, 2001, pp. 380–384. Original Russian Text Copyright ? 2001 by Livshits, Egorov, Kochnev, Kapitonov, Lantratov, Ledentsov, Nalyot, Tarasov. Deceased.     

Performance and reliability of high radiance InGaAsP/InP DH LED́s operating in the 1.15-1.5 µm wavelength region

The performance and reliability of InGaAsP/InP double heterostructure (DH) light emitting diodes (LED's) have been investigated over a wide range of emission wavelengths1.15-1.5 mum. High radiance performance has been achieved by growing optimized DH structures and adopting a method of coupling a monolithic-lensed LED to a spherical-ended fiber. Interface instability previously encountered in the liquid phase epitaxy (LPE) to grow a DH for 1.5 μm wavelength has been eliminated by a new growth method using a reduced temperature. LED's exhibiting typical output powers of 50, 44, and 21 μW at 100 mA, measured at the end of a 50 μm core 0.20 NA graded-index fiber with a length of 1 m, have been realized, respectively, at wavelengths of 1.15, 1.27, and 1.5 μm. The spectral width, coupled power and its temperature dependence, and the cutoff frequency have been analyzed in terms of the emission wavelength. Operating lives of LED's at three different wavelengths have been estimated from the result of accelerated aging carried out at the ambient temperature of 200°C and at a constant current of 100 mA. It has been found that the degradation rate exhibits no dependence on the wavelength confirming the same value of half-lives in excess of 10⁹h for the 60°C operation.     

A 1.58 nW power consumption and 34.45 ppm/°C temperature coefficient bandgap reference (BGR) for subblocks of RFID tag

In this paper a bandgap reference (BGR) circuit irrespective of the temperature and the supply voltage variation with very low power consumption is proposed. The proportional to absolute temperature (PTAT) and complementary to absolute temperature (CTAT) generators of the proposed BGR, which has four cores cascaded with each other, are used in order to increase not only the output voltage, but also the output control ability for the temperature and the voltage insensitivity. To combine produced voltage from PTAT and CTAT generator, a weight combination circuit, which uses internal capacitors of transistors, is applied. Due to the fact that all of the transistors in such a topology are worked in sub-threshold region, the power consumption is significantly diminished to 1.58 nW. Also the variation of the temperature from −25 °C to 150 °C, leads to the temperature coefficient about 34.45 ppm/°C. The design simulation is done at 960 MHz frequency in TSMC 0.18 µm CMOS technology with the help of Cadence software. Also the post layout simulation result and the layout of the proposed circuit are presented. The output and the chip area of this BGR are 141.5 mV and 1387 µm² respectively.     

Temperature‐Adaptive Back‐Bias Voltage Generator for an RCAT Pseudo SRAM

In order to guarantee the proper operation of a recessed channel array transistor (RCAT) pseudo SRAM, the back‐bias voltage must be changed in response to changes in temperature. Due to cell drivability and leakage current, the obtainable back‐bias range also changes with temperature. This paper presents a pseudo SRAM for mobile applications with an adaptive back‐bias voltage generator with a negative temperature dependency (NTD) using an NTD VBB detector. The proposed scheme is implemented using the Samsung 100 nm RCAT pseudo SRAM process technology. Experimental results show that the proposed VBB generator has a negative temperature dependency of ?0.85 mV/°C, and its static current consumption is found to be only 0.83 µA@2.0 V.     

Harmonic oscillation using Λ-shaped negative resistance device

The oscillator performance of A-shaped negative resistance devices is numerically analyzed. The most distinguished feature revealed is that the Λ-shaped device shows a monotonic increase of output power with increasing bias voltage. A maximum oscillation efficiency as high as 94 percent is predicted.     

半导体照明光源恒流驱动芯片的研究

介绍了一种半导体照明光源恒流驱动芯片的设计。该芯片采用0.6μm CM O S标准工艺制造,包含有大功率M O SFET、带隙基准源电路、输出缓冲电路和取样反馈控制电路几个主要功能模块,在标准工艺线上实现了功率器件与控制电路的单片集成。该芯片可为工作电压为3.5 V,工作电流为350 mA的单个半导体照明光源提供恒定的驱动电流。在5 V电源电压有10%跳变的情况下,半导体照明光源的驱动电流的变化可被控制在1.71%以内,而距离光源10 cm处的照度变化仅为1.28%。当环境温度由25°C升高至85°C时,半导体照明光源的驱动电流减小1.14%,而距离光源10 cm处的照度仅减小1.09%。该恒流驱动芯片的电源效率可达63.4%。     

Thermal effects in double prism dye laser cavities

Output power, beam divergence, and frequency stability in a double-prism dye laser cavity have been investigated as a function of temperature. For rhodamine 6G dye, it has been found that output power decreases by nearly 34 percent, beam divergence increases from 4.5 to 6.5 mrads, and the laser frequency is shifted by as much as 2 cm^-1, for an increase of 10°C above room temperature. The efficiency of the double-prism dye laser oscillator employed here was 18 percent (for N2laser pump) at a linewidth of 0.07 cm^-1(FWHM). Laser linewidth did not vary in the temperature range investigated here.     

The temperature dependence of the CH3F far infrared laser output

The output power of an optically pumped far infrared waveguide laser has been measured for the laser gas CH3F between -100 and +100°C. At -30°C, an enhancement by a factor of about 3.5 over room-temperature operation has been found. The experimental data are compared with a recent theoretical treatment; the output power drops more rapidly than predicted towards both high and low temperature.     

InGaAsP/InP separated multiclad layer stripe geometry laser emitting at 1.5 µm wavelength

We have developed an InGaAsP/InP separated multiclad layer (SML) stripe geometry laser emitting at 1.5 μm wavelength. In this laser, the optical confinement is done by the effective refractive index step owing to the formation of the coupled waveguide outside the stripe region. The current confinement is done by the p-n-p-n structure outside the stripe region. The CW threshold current at 25 °C is only 82 mA for the stripe width and the cavity length of 6 μm and 250 μm, respectively. The maximum temperature where the CW lasing is obtained is 65°C. The characteristic temperature of the threshold current is 60 K. The transverse mode is fundamental up to 1.8 times the threshold. Ten samples are operated at 50°C with constant optical output of 5 mW/facet. These samples are still operating at over 10 000 h with a slight increase in the driving current. The appreciable change in the characteristics due to aging is not observed.     

Development of Broad Band VCO at Ka-Band

A broad band VCO has been developed at Ka-band for FMCW Radar applications. To achieve a wide range of frequency variation, VCO has been designed in series configuration. Design steps have been presented. VCO exhibits a tuning range of 600 MHz with the power output of 50 mw, when the controlled varactor voltage varies from 7.5 volts to 15 volts. Frequency drift with temperature has been contained within 30 MHz using a proportionally controlled DC heater module over the temperature range of 0°C to +55°C. Phase Noise of the oscillator measured at the mid and extreme frequencies is about -70 dBc/kHz at 10 kHz away from the carrier. The experimental circuit and measured performance is also presented.     

Elevated temperature nitrogen implants in 6H-SiC

Elevated temperature (700°C) N ion implantations were performed into 6H-SiC in the energy range of 50 keV-4 MeV. By analyzing the as-implanted depth distributions, the range statistics of the N⁺ in 6H-SiC have been established over this energy range. Annealing at 1500 and 1600°C for 15 min resulted in Rutherford backscattering spectrometry scattering yields at the virgin crystal level, indicating a good recovery of the crystalline quality of the material without any redistribution of the dopant. A maximum electron concentration of 2 × 10¹⁹ cm⁻³, at room temperature, has been measured even for high-dose implants. The p-n junction diodes made by N ion implantation into a p-type substrate have a forward turn-on voltage of 2.2 V, an ideality factor of 1.90, and a reverse breakdown voltage of 125 V with nA range leakage current for -10 V bias at room temperature. By probing many devices on the same substrate we found uniform forward and reverse characteristics across the crystal.     

A novel millimeter wave gunn oscillator

It is described that the design, configuration and the performance of a novel millimeter wave Gunn oscillator stabilized by external cavity and temperature compensation in this paper. The frequency stability is 3.6 × 10^?6 at 52 GHz over the teperature range from ?10 to 50 °C. An output power of more than 100mW has been obtained in the frequency range from 51.5 to 52.8 GHz.     

InGaAsP double-channel- planar-buried-heterostructure laser diode (DC-PBH LD) with effective current confinement

A new high-performance 1.3-μm InGaAsP semiconductor laser is described, in which effective current confinement into the active region has been realized. A p-n-p-n current blocking structure is made by liquid-phase epitaxy (LPE) on both sides of the active-stripe mesa which is defined by a pair of channels in the double-heterostructure wafer. The double-channel-planar-buried-heterostructure laser diodes (DC-PBH LD's) exhibit high-laser performances, such as a high differential quantum efficiency of 78-percent maximum, which results in high electrical to optical power conversion efficiency 43 percent, and high light output power of over 50 mW, as a result of the improvement in the current blocking structure. The threshold current temperature sensitivity is found experimentally to be reduced remarkably by increasing the doping concentration in the p-cladding layer. Characteristic temperature as high as 100 K has been obtained. CW operation is possible up to 130°C.     

ISO 14443单芯片读卡机发射电路的设计

介绍一种新的CMOS功率放大电路,该电路既有开关型放大器的高效率的特点,同时又具备线性功率放大电路能输出可变包络的特点,而且可以根据实际需要对输出功率进行调节。电路在0.6μm工艺线上流片。经测试验证电路能在-20°C～80°C的温度范围内工作,工作电压范围为2.5V～5.5V,输出功率可在很大范围内进行调节,在5V条件下,最大输出功率可达6.25W。