Gain and threshold-current calculation of V-groove quantum-wire InGaAs-InP laser

This paper presents material-gain and threshold-current calculation of a InGaAs-InP quantum-wire laser in the framework of the k/sub /spl middot//p method, with included conduction-band nonparabolicity for the first time. The method for band-structure calculation is based on conformal mapping and Fourier expansion. The calculation shows that high material gain (7000 cm/sup -1/) can be achieved at room temperature for polarization along the free axis of the quantum wire. We propose an optimized laser structure, based on a stack of quantum wires.     

Model of Improved Arc Generator for Fullerene Production

Process of fullerene formation and fragmentation is studied in various zones of fullerene generator. Fullerenes are produced utilizing carbon arc method, in which graphite electrodes are vaporized in a low pressure helium atmosphere by passing an electrical current through the electrodes. The effects of the gas pressure and intensity of the direct current on fullerene yield are investigated. Maximum fullerene yield of 8% is found in a raw soot after the evaporation of graphite by a 60 A direct current, in a helium ambient under the pressure of 8 kPa.     

Bulk-Micromachined Test Structure for Fast and Reliable Determination of the Lateral Thermal Conductivity of Thin Films

A novel bulk-micromachined test structure is presented for the fast and reliable determination of the lateral thermal conductivity of thin films. The device is composed of a heater resistor and thermocouples that are fabricated in polysilicon (poly-Si), and the associated processing and DC measurement procedures are straightforward. The validity of the method is supported by numerical simulations and verified by experimental determination of the lateral thermal conductivity of aluminum (Al), aluminum nitride (AlN), p-doped poly-Si, and silicon nitride (SiN) thin films. For Al, an average value of 217 W m^-1 K^-1 was found for 1-mum thick layers. For the other layers, a number of thicknesses were studied, and the increase of thermal conductivity with thickness was effectively detected: for AlN, values from 7 to 11.5 W m^-1 K^-1 were found, and for p-doped poly-Si, values went from 21 to 46 W m^-1 K^-1 for thicknesses from 0.15 to 1 mum. For SiN, a value of 1.8 was extracted for layers thicker than 0.5 mum.     

Extraction and modeling of self-heating and mutual thermal coupling impedance of bipolar transistors

A measurement system comprised of an ultra-low-distortion function generator, lock-in amplifier, and semiconductor parameter analyzer is used for sensitive extraction of the small-signal thermal impedance network of bipolar devices and circuits. The extraction procedure is demonstrated through measurements on several silicon-on-glass NPN test structures. Behavioral modeling of the mutual thermal coupling obtained by fitting a multipole rational complex function to measured data is presented.     

A back-wafer contacted silicon-on-glass integrated bipolar process. Part I. The conflict electrical versus thermal isolation

A novel silicon-on-glass integrated bipolar technology is presented. The transfer to glass is performed by gluing and subsequent removal of the bulk silicon to a buried oxide layer. Low-ohmic collector contacts are processed on the back-wafer by implantation and dopant activation by excimer laser annealing. The improved electrical isolation with reduced collector-base capacitance, collector resistance and substrate capacitance, also provide an extremely good thermal isolation. The devices are electrothermally characterized in relationship to different heat-spreader designs by electrical measurement and nematic liquid crystal imaging. Accurate values of the temperature at thermal breakdown and thermal resistance are extracted from current-controlled Gummel plot measurements.     

A back-wafer contacted silicon-on-glass integrated bipolar process. Part II. A novel analysis of thermal breakdown

Analytical expressions for the electrothermal parameters governing thermal instability in bipolar transistors, i.e., thermal resistance R/sub TH/, critical temperature T/sub crit/ and critical current J/sub C,crit/, are established and verified by measurements on silicon-on-glass bipolar NPNs. A minimum junction temperature increase above ambient due to selfheating that can cause thermal breakdown is identified and verified to be as low as 10-20/spl deg/C. The influence of internal and external series resistances and the thermal resistance explicitly included in the expressions for T/sub crit/ and J/sub C,crit/ becomes clear. The use of the derived expressions for determining the safe operating area of a device and for extracting the thermal resistance is demonstrated.