摘要:

This paper describes the use of a fully automated Fourier‐transform infrared spectrophotometer system to scan the composition of bulk slices of CdxHg1−xTe for the range 0.15<x< 0.35 and its calibration to analytically determinedXvalues. The most useful correlation established is for thentype, between the 300 K IR cuton defined by the zero‐transmission intercept of a line tangent to the transmission curve at 1/eof its maximum and the composition parameterXas determined by wet chemical analysis. The overall prediction accuracy of trueXis better than 0.005. Other cuton definitions, implementation pitfalls, andXcorrelations with bothp‐type transmission and 300 K carrier concentration are also discussed.

ISSN:0021-8979    

DOI:10.1063/1.341056

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The distributed nature of the reflection process is considered for pump‐and‐probe‐type picosecond transient thermoreflectance (PTTR) measurements. A first‐order approximation is given for the temporal dependence of the reflectivity for temperature distributions created by picosecond laser pulses. It was found that PTTR flashes back the temperature profile created by the pump pulse. The problem of determining the thermal transport properties from PTTR measurements is discussed.

ISSN:0021-8979    

DOI:10.1063/1.341057

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Optical absorption and photoluminescence measurements were made on Cd0.9Mn0.1Te doped with As, P, Cu, and Au. Shallow acceptor ionization energies were determined as: 108 meV for P; 115 meV for As; 170 meV for Cu; and 180 meV for Au. These energies are larger than those for CdTe due to the formation of bound magnetic polarons. Self‐consistent numerical calculations of the bound magnetic polarons are made for As and P dopants. The absorption spectra below 0.5 eV were separated into contributions from acceptor photoionization, inter‐ and intraband transitions, and free‐hole absorption. Acceptor concentrations in the 1017cm−3range were found for As and P doping; however, Cu and Au were found to produce high compensation (<1012cm−3). Mechanisms for this behavior are discussed.

ISSN:0021-8979    

DOI:10.1063/1.341058

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Polycrystalline Pd2Si is found to reorder on top of epitaxial Pd2Si during silicide growth. The interface between polycrystalline Pd2Si and epitaxial Pd2Si is, thus, not immobile with respect to the silicide lattice during silicide formation and it is, therefore, not possible to use this interface as a structural marker in order to monitor diffusion in epitaxial Pd2Si. The use of Ti as an inert marker has shown that Si is the dominant diffusing species in epitaxial Pd2Si during silicide formation.

ISSN:0021-8979    

DOI:10.1063/1.341059

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The fractional contributions of the various SiHnradicals (n=0–3) to deposition are calculated for low‐power, pure‐silane rf and dc discharges. This is done using a radical diffusion plus reaction equation, combined with current knowledge of SiH4dissociation fractionation, of SiHn+SiH4reactions, and of the distributed source of radicals. The conclusion reached is that more than 98% of neutral radical deposition is by SiH3for typical deposition pressures (>100 mT at 240 °C). The effect of SiH3+SiH3reactions at higher power is also evaluated using an estimated reaction rate coefficient (k3). The resulting loss in deposition rate is given as a function of film growth rate and ofk3.

ISSN:0021-8979    

DOI:10.1063/1.341034

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Structures consisting of alternate layers of Mo/Ti and W/Ti have been sputter deposited on Si(100) substrates and their annealing behavior has been studied using Auger sputter profiling. The anneals were performed under typical processing conditions. Two major driving forces control the observed reactions: the silicidation of the metals and the oxidation of Ti. The prevalence of one of them depends both on the structure of the as‐deposited film and on the annealing temperature. In the case where silicidation prevails a multisilicide layer is formed, with no alteration with respect to the initial disposition order of the metal films. Intermixing between the reacted layers starts to be observed at 900 °C. The behavior of common contaminants such as oxygen and carbon has been studied.

ISSN:0021-8979    

DOI:10.1063/1.341035

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The photovoltage variation with redox potentialERedis investigated onp‐InP andp‐CuInS2for various surface treatments. Etching and ion chemisorption are shown to successively improve CuInS2photovoltagesVPhresulting in a slope of ∼1 ofVPhvsERed. The respective densities of states are determined using a model calculation yieldingDs≊6×1011states cm−2 eV−1andDs≊1.2×1014states cm−2 eV−1for the unpinned and pinned situation, respectively. Good agreement between the calculated voltage drop in the Helmholtz layer due to CuInS2Fermi‐level pinning (FLP) and the missing photovoltage is obtained in a simple model calculation based on the surface state charge density. InP photocathodes show aVPhvsEReddependence in the dark, depending on pretreatment which is attributed to a chemical reaction that inhibits Fermi level equilibration. Positive from −0.4 V (SCE)VPhis independent ofERedfor polished and etched surfaces. The independence is explained assuming a dynamic equilibrium between semiconductor and solution without band‐edge shifting. At the potential wherep‐InP solar cells are operated (−0.47 V vs SCE), the electrodes behave as unpinned.

ISSN:0021-8979    

DOI:10.1063/1.341036

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Transport of photoelectrons by the ⟨110⟩ propagating surface acoustic wave (SAW) on (100)‐cut gallium arsenide was observed using the acoustic charge transport (ACT) principle reported by Hoskins, Morko&Vthgr;, and Hunsinger [Appl. Phys. Lett.41, 332 (1982)]. By directly modulating an AlGaAs light‐emitting diode, pulses of near‐infrared radiation (&lgr;p=730 nm) were applied to semitransparent (25 nm thick) chromium windows on the device surface. Four such windows separated by 250 &mgr;m were positioned along the otherwise opaque Schottky channel plate of the ACT device. Electron‐hole pairs generated by incident radiation were separated by the electrostatic field in the depletedn‐type channel region. Calculations suggested that the separation time would be small enough to reduce radiative recombination and allow enough electrons to collect in each acoustically defined well passing beneath the injection window for detection at the output. Electrons, separated from the holes, were subsequently bunched and carried along by the electric field coupled to the SAW. Output pulse delays for injection over each window were in agreement with theory taking into account the window positions and the SAW velocity (2864 m/s). Quantum efficiency, defined as the number of electrons collected at the output per incident photon on the chromium window, was approximately 0.09. Operated at 360 MHz, the experimental device had a charge transfer efficiency in excess of 0.992. It is believed that the injection technique described may be of use in future optical signal processing or imaging applications using ACT.

ISSN:0021-8979    

DOI:10.1063/1.341037

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A field‐effect transistor (FET) using a solid electrolyte is proposed in the present study as a new oxygen sensor. The sensor is fabricated by depositing a thin layer of yttria‐stabilized zirconia (YSZ) on a gate insulator of an insulated gate field‐effect transistor (IGFET). As an IGFET has an ability to transform impedance, the potential change produced at the interface between the YSZ layer and a platinum gate electrode can be detected stably, even if the impedance of the YSZ is very high. The response of the fabricated sensor showed good reproducibility at 20 °C. A linear relationship between output voltage and logarithmic partial pressure of oxygen was obtained in the range from 0.01 to 1 atm. Sensitivity of the sensor was found to depend on the thickness of the Pt‐gate electrode and sputtering conditions of the YSZ layer. Although selectivity to hydrogen and carbon monoxide was not good at room temperature, it could be improved by increasing the operating temperature to 100 °C. The developed sensor has several advantages including small size, low output impedance, and solid‐state construction. It is potentially applicable to medical uses, process control, and automobiles.

ISSN:0021-8979    

DOI:10.1063/1.341038

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The cutoff wavelength &lgr;coat 77 K of implantedn+‐on‐bulkp‐type Hg1−xCdxTe photodiodes is calculated with the minority‐carrier lifetime of the bulk material as a parameter: 1.24/&lgr;co=[T+81.9/3.267×104(1+x)] {18.88−53.61x− 1/2  ln [(kT/q) &mgr;n&tgr;n]} −0.3424+1.838x+0.148x4(eV). The compositionxis obtained from the zero‐intercept transmission spectra measured at 300 K. The minority‐carrier lifetime &tgr;nof the photodiodes and its temperature dependence have been obtained from the photodiode dynamic resistance at zero‐bias voltage versus reciprocal temperature 1/Tdata. The temperature dependence of the minority‐carrier mobility &mgr;nis also taken into account. The results indicate that the lifetime in the bulkp‐type material is determined by Shockley–Read generation‐recombination centers. For undoped,p‐type substrates obtained from Cominco Inc., the trap energy is approximately 45 meV. Gold‐doped crystals grown by the method of solid‐state recrystallization exhibit a trap energy of the order of 30–35 meV.

ISSN:0021-8979    

DOI:10.1063/1.341039

出版商:AIP    

年代:1988

数据来源: AIP