The process to decrease the dislocation density in 3-inch Fe-doped InP wafers is described. The crystal growth process is a conventional liquid encapsulated Czochralsky (LEC) but thermal shields have been added in order to decrease the thermal gradient in the growing crystal. The shape of these shields has been optimized with the help of numerical simulations of heat transfer and thermomechanical ...
The density and light-scattering intensity of oxygen precipitates in CZ silicon crystals are measured by IR light-scattering tomography. The numerical data clarified through the measurements are discussed in relation to the amount of precipitated oxygen. The results obtained here correspond well with the theoretical analysis that oxygen precipitates cause light to scatter. The information obtained...
Ion beam irradiation has been examined as a method for creating nanoscale semiconductor pillar and cone structures, but has the drawback of inaccurate nanostructure placement. We report on a method for creating and templating nanoscale InAs spikes by focused ion beam (FIB) irradiation of both homoepitaxial InAs films and heteroepitaxial InAs on InP substrates. These 'nanospikes' are created as In ...
To realize high-performance silicon carbide (SiC) power devices, low-resistance ohmic contacts to p-type SiC must be developed. To reduce the ohmic contact resistance, reduction of the barrier height at metal/SiC interfaces or increase in the doping concentration in the SiC substrates is needed. Since the reduction of barrier height is extremely difficult, the increase in the Al doping concentrati...
In this paper, using a fully-coupled, three-dimensional electro-thermal device simulator, we study the mechanism of efficiency degradation at high current operation in planar GaN-based light emitting diodes (LED). In particular, the improvement of the efficiency degradation using thicker conductive GaN substrates has been demonstrated. First, it is found that local Joule heating inside thin conduc...
We present a non-contact method for the determination of the thermal response time of temperature sensors embedded in wafers. In this method, a flash lamp illuminates a spot on the wafer in periodic pulses; the spot is on the opposite side from the sensor under test. The thermal time constant of the sensor is then obtained from measurement of its temporal response, together with a theoretical mode...
We have improved the efficiency of photoconductive antennas (PCAs) using low-temperature-grown GaAs (LT-GaAs). We found that the physical properties of LT-GaAs photoconductive layers greatly affect the generation and detection characteristics of terahertz (THz) waves. In THz generation, high photoexcited carrier mobility and the presence of a few As clusters in the LT-GaAs are two important factor...
A contactless non-destructive imaging method for spatially resolved dopant concentration, [2.2] N d, and electrical resistivity, ρ, of n- and p-type silicon wafers using lock-in carrierography images at various laser irradiation intensities is presented. Amplitude and phase information from wafer sites with known resistivity was employed to derive a calibration factor for accurate determination of...