摘要:

Three different groups of metal‐oxide‐semiconductor devices were manufactured of bond‐and‐etchback silicon‐on‐insulator wafers where the buried oxide functioned as the gate dielectric. The groups differed in the procedure used to clean the surfaces prior to bonding and in the location of the bonded interface. The surfaces were cleaned using either the standard RCA cleaning procedure without HF dip or by rinsing in de‐ionized water only. The location of the bonded interface was in the buried oxide or at its interface toward a silicon wafer. The RCA‐cleaned devices with the bonded interface within the buried oxide were found to degrade severely under bias temperature stress. This degradation was evident from both oxide charging and an increase in the density of states at the Si/SiO2interface for negative gate biases. For positive biases the most prominent effect was lateral nonuniform charging of the oxide. The lateral nonuniformities might be connected to voids formed by ammonia desorption during postbonding annealing. Devices rinsed in de‐ionized water prior to bonding and devices with a homogeneous oxide showed only slight degradation after bias temperature stress. Electron injection by internal photoemission showed that the buried oxides contained electron traps with capture cross sections corresponding to Coulomb attractive traps. The different processing conditions did not affect the trap cross section but influenced the trap densityNt. Devices with the bonded interface within the buried oxide hadNt≊1×1011cm−2in the case of RCA cleaning andNt≊4×1010cm−2for de‐ionized water rinsing. The devices with a homogeneous oxide hadNt≊4×109cm−2. Electron trapping in the Coulomb attractive traps was accompanied by a corresponding increase in the density of states at the thermally grown Si/SiO2interface for devices with a bonded buried oxide. SIMS investigations revealed a correlation between the degradation upon stress and hydrogen concentration in the devices with bonded oxides. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359979

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The aim of this work is to provide the basis for the interpretation, under steady state and in the low‐voltage regime of the dark current‐density–voltage (J–V) characteristics of transverse asymmetric amorphous silicon (a‐Si:H)p‐i‐nandn‐i‐pdiodes. The transverse asymmetrica‐Si:H diodes present ratios between the metal contact and the underneath doped layer areas larger than five, leading to the inclusion, in the diode equation, of a lateral leakage current, responsible for the high saturation current density and the forward shape of theJ–Vcurves recorded. The leakage current depends on the lateral spatial potential developed with which varies following a power‐law dependence. The experimentalJ–Vcurves in diodes with the doped layer around the metal contact unetched and etched prove the role and origin of this lateral leakage current and, thus, the proposed model. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359980

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new metal‐semiconductor field‐effect‐transistor surface characterization technique is presented. The complex impedance (magnitude and phase) between the source and drain contacts is measured as a function of frequency and temperature. It is shown that the phase data exhibit peaks in the frequency spectrum that correspond to characteristic emission rates for surface‐state traps. Measurements at different temperatures provide the energetic position and capture cross section of dominant traps. The technique provides a relatively rapid surface characterization tool in comparison to deep‐level transient spectroscopy. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359981

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report our simulation results for the dynamic characteristics of single‐transit SiC SiC impact‐ionization avalanche transit‐time (IMPATT) diodes. An iterative Monte Carlo–Crank‐Nicholson technique has been used to solve the coupled electron transport‐heat conduction problem. This procedure allows for accurate computation of both the device current as a function of temperature, time, and position, and the internal heat generation. The technique is quite general, has not been used before, and can be applied for the analysis of any power device. Our results show that the internal power generation profile within the SiC IMPATT device can have a very nonuniform axial distribution. The internal heating is seen to significantly degrade the device efficiency and optimum operating frequency. With thermal effects the output current values are lower and the transit time is increased. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359982

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Comprehensive comparison between theory and experiment has been made on the characteristics of a high‐Tcdc superconducting quantum interference device (SQUID). Using the theoretical expressions for the SQUID characteristics, we can quantitatively predict the transfer functionV&fgr;and the magnetic‐flux noiseS&Fgr;from SQUID parameters without any adjustable parameter. It is shown that the theoretical predictions agree well with the experimental results for a wide range of SQUID parameters. This agreement shows the usefulness of the present theory in the design of the high‐TcSQUID. Exceptional deviations between theory and experiment are the absolute values, i.e., the factor of 0.6 difference inV&fgr;and the factor of 10 difference inS&Fgr;. Possible reasons for these discrepancies are discussed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359983

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have investigated theoretically the electronic subband structures and the scattering probability of electrons by ionized impurities in &dgr;‐doped field‐effect transistors (&dgr;‐FETs). The self‐consistent calculation of the Poisson and Schro¨dinger equations shows that the electrons are quite extended, even though the impurities are very much confined (&dgr; doped). It is shown that the impurity scattering probability decreases if the carriers and impurities are well separated spatially, or if the kinetic energies of the carriers are large. For both the singly and doubly &dgr;‐FET, the averaged kinetic energies of the carriers are increased when the sample temperature is increased; the carriers are pushed away from the &dgr;‐doped impurity layers when the gate bias is increased. The combination of the two effects result in an enhanced electron mobility, as demonstrated by experiments. Our detailed numerical calculation thus provides us with some basic guidelines to improve the performance of &dgr;‐FETs: Multiple &dgr;‐doped layers and a high sheet density are desirable. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359984

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

To study the growth mechanism in growing superconducting thin films by the liquid‐gas‐solidification process, oxygen diffusivities in liquid Tl1Ba2Ca2Cu3and Ag1Tl1Ba2Ca2Cu3precursor alloys were measured by a modified coulometric titration method. The diffusivities of oxygen are very high of the order of 10−4to 10−3cm2/s. The logarithm of oxygen diffusivities is found to be reciprocally proportional to the logarithm of oxygen concentrations. This concentration‐dependent oxygen diffusivity phenomenon has not been observed in many metallic liquids investigated previously. An interstitial diffusion mechanism may contribute to the fast oxygen diffusion. The strong bonds between Ba and O atoms are proposed to enhance the configurational structural order and hence to quicken the oxygen diffusion that varies the oxygen concentration in Tl1Ba2Ca2Cu3and Ag1Tl1Ba2Ca2Cu3superconductor precursor liquids. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359985

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An improved way to solve the wave equation for the graded‐index planar waveguide is presented. An analytic solution correct up to the first order of the dielectric function gradient is obtained for a linearly graded medium and is applied to calculate the optical confinement factors in a number of graded‐index waveguides of laser diode structure. For a multilayer sectioning method, the number of section layers required to get a reasonable error is greatly reduced by considering the gradient in each sectioned layer instead of using the average value, especially in the case of linear grading. The advantages and limits of the solution are discussed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359986

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Tensile‐strained GaAs0.89P0.11/Al0.33Ga0.67As quantum wells have been grown by low‐pressure metalorganic vapor phase epitaxy. The grown samples have been studied by low‐temperature (6 K) and 100 K in‐plane photoluminescence as well as cross‐sectional polarized photoluminescence measurements. The experimental results show the coincident or reversal point of the light‐ and heavy‐hole related transitions at the well width of 60 A˚, above which the low‐temperature photoluminescence is given by the transition 1e–1lh. A theoretical calculation agrees well with the experimental results. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359987

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The photoluminescence band in porous Si is found to shift monotonically toward lower energy at a rate of −(18±5) meV/GPa if a hydrostatic pressure of up to 5 GPa is applied with liquid argon, in contrast to a convex behavior of the shift observed when a methanol–ethanol mixture is used as the pressure‐transmitting medium. The data show that the electronic energy gap relevant to the luminescence is intrinsically reduced by the hydrostatic compression but has a distinct solvatochromic character. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359988

出版商:AIP    

年代:1995

数据来源: AIP