摘要:

Evaporated ZnS:Mn alternating-current thin-film electroluminescent (ACTFEL) devices are assessed via frequency- and temperature-dependent transferred charge analysis. The frequency-dependent trends involve the threshold voltage and the slope of the transferred charge immediately above threshold, both of which increase with increasing frequency. At ∼15–20 V above threshold, the slope of the transferred charge curve is relatively independent of frequency and is approximately equal to the physical insulator capacitance. The temperature‐dependent trends indicate that the phosphor capacitance increases and the slope of the transferred charge immediately above threshold decreases with increasing temperature. These frequency‐ and temperature‐dependent trends are interpreted as arising from metastable hole trapping in which holes created in the phosphor by band‐to‐band impact ionization remain trapped in metastable traps at the cathode interface instead of being annihilated by electrons trapped at interface states. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364127

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

An analytical model is proposed to understand backgating in GaAs metal–semiconductor field-effect transistors (MESFETs), in which the effect of channel–substrate (CS) junction is included. We have found that the limitation of CS junction to leakage current will cause backgate voltage to apply directly to CS junction and result in a threshold behavior in backgating effect. A new and valuable expression for the threshold voltage has been obtained. The corresponding threshold electric field is estimated to be in the range of 1000–4000 V/cm and for the first time is in good agreement with reported experimental data. More, the eliminated backgating effect in MESFETs that are fabricated on the GaAs epitaxial layer grown at low temperature is well explained by our theory. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364129

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report a novel metal–insulator–semiconductor (MIS) structure exhibiting a pseudomorphic In0.05Ga0.95As layer on GaAs with interface state densities in the low 1011eV−1 cm−2. The structure was grown by a combination of molecular beam epitaxy and chemical vapor deposition methods. The hysteresis and frequency dispersion of the MIS capacitor were lower than 100 mV, some of them as low as 30 mV under a field swing of about ±1.3 MV/cm. The 150-Å-thick In0.05Ga0.95As channel between Si and GaAs is found to bring about a change in the minority carrier recombination behavior of the GaAs channel, in the same way as done by In0.53Ga0.47As channel MIS structures. Self-aligned gate depletion mode In0.05Ga0.95As metal–insulator–semiconductor field-effect transistors having 3 &mgr;m gate lengths exhibited field-effect bulk mobility of 1400 cm2/V s and transconductances of about 170 mS/mm. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364130

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Nuclear transmutation is employed in an investigation of copper doping in ZnSe. Copper atoms are introduced at zinc sites in ZnSe after crystal growth processes are complete. Since the copper dopants are introduced after growth, far from equilibrium, they are less able to form complexes with other dopants or lattice defects as they may do when present during crystal growth. Initial results are consistent with CuZnbeing involved in the copper red and copper green emissions in ZnSe but not in the I1dexitonic emission. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364131

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The phase transformation of graphitelike BN (h-BN) to wurtzite-type high-pressure BN (w-BN) was investigated through shock-recovery techniques under quasihydrodynamic and nonhydrodynamic shock compressions and under various strain conditions. The experimental results support a diffusionless mechanism, by which the hydrodynamicc-axis compression ofh-BN is preferred. This mechanism is topologically considered based on the relationship of crystal structures betweenh-BN andw-BN. The presence of deviatoric stress and strain depresses the yield ofw-BN and the development ofw-BN (100) relative to (002). ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364132

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Electronic potential profile, energy levels, and their respective occupations are self-consistently calculated for &dgr;-doped semiconductor films, taking into account the charge depleted by the surface. This effect is considered by requiring the Fermi level at the surfaces to be at some fixed value relative to the band gap edges. The electron concentration in the potential well is calculated for different values of the film thickness and of the surface chemical potential. The results show that these calculations can be helpful in determining the Fermi level pinning at the surface by fitting Hall concentrations of &dgr;-doped samples.©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364092

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Bi2Sr2CaCu2Oy(Bi2212) crystals with CuO inclusions were grown on the surface of KCl flux. The density of CuO incorporations of 109/cm2was similar to that for Y2BaCuOyin melt-textured YBa2Cu3Oy. The CuO inclusions are needlelike particles with diameter of less than 1 &mgr;m. Magnetization measurements show enhanced flux pinning at high magnetic field, compared to crystals without CuO. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364093

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We describe a straightforward technique for the measurement of carrier diffusion in semiconductors. Using an optical microscope we can spatially image luminescence with a resolution of ∼500 nm. We measured the ambipolar diffusion length in a Zn0.75Cd0.25Se–ZnSe single quantum well by fitting the spatially resolved luminescence profile with the solution of the two-dimensional diffusion equation. The ambipolar diffusion length was found to be 498 nm at a carrier density of ∼1×1018cm−3and we deduce an ambipolar diffusion constant of 1.7 cm2 s−1. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364094

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Angle velocity distributions of 532 nm laser sputtered gold atoms are measured. No emission is seen at low fluence unless melt structure is first induced on the gold surface. Following melting, the velocity distribution at 1.4 J/cm2is Boltzmann at 6500 K and the angular distribution is cosine. At 4.9 J/cm2the angle velocity distribution shows collisional modification. These data contradict thermal sputtering but may result from surface plasmon excitation. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364095

出版商:AIP    

年代:1997

数据来源: AIP