Fabrication and characterization of the amorphous-silicon staticinduction transistor

Experimental results for the fabrication and electrical characterization of a hydrogenated amorphous silicon static induction transistor are reported. The I-V measurements demonstrate the triode-like enhancement mode operation of the device and show an on-off current ratio of 300 and a pinchoff voltage of -9.5 V for V_ds=6 V. Numerical simulation suggests that the differences between experimental and theoretically predicted results are due to the presence of a high-density-of-states layer at the a-Si:H/a-Si:H interface     

Light-to-input nonlinearities in an R-LED series network

The light-to-current (L-I) and light-to-voltage (L-V) differential nonlinearities in the simple network of a customary LED and an external resistor R in series are analyzed and calculated theoretically and compared with experimental data. Particular emphasis is placed on the influence of the log-arithmetic slope ν of the L-I characteristic and the bias current I upon the ratio of the corresponding nonlinearity parameters. It is thus deduced that, for a given optical power P, over superlinear portions of the L-I curve (ν>1) the L-I linearity is typically better than its corresponding L-V linearity. On the contrary, when the L-I dependence is sublinear (ν<1) the voltage driving scheme may ensure for the R-LED network, or the LED alone, a local L-V response much more linear than the L-I response, provided that appropriate (optimum) I and/or R values are chosen     

An analytical model for I-V and small-signalcharacteristics of planar-doped HEMTs

An analytical current-voltage (I-V) model for planar-doped HEMTs is developed. This compact model covers the complete range of I-V characteristics, including the current saturation region and parasitic conduction in the electron-supplying layer. Analytical expressions for the small-signal parameters and current-gain cutoff frequency are derived from the I-V model. Modeling results for a 0.1-μm-gate planar-doped AlInAs-GaInAs HEMT show excellent agreement with measured characteristics. Threshold voltages and parasitic conduction in planar-doped and uniformly doped HEMTs are also compared and discussed     

Frequency-dependent capacitance-voltage characteristics foramorphous silicon-based metal-insulator-semiconductor structures

A frequency-dependent capacitance-voltage model for the a-Si:H-based MIS structure is presented along with an alternative direct measurement method. The static C-V model is derived based on the static I-V model developed using the simplified CFO band model for the a-Si bulk bandgap states and the simplified Davis-Mott model for the surface states. The frequency variation of the measured capacitance, using a somewhat modified TFT, is modeled with the lateral flow transmission line model. These models can be used to monitor TFT-fabrication parameters and to extract accurate capacitance model parameters of TFTs     

A complete model of the I-V characteristics fornarrow-gate MOSFETs

A unified and process-independent MOSFET model for accurate prediction of the I-V characteristics and the threshold voltages of narrow-gate MOSFETs is discussed. It is based on several enhancements of the SPICE2 LEVEL3 MOS model and the author's previous subthreshold I-V model. The expressions achieved for the drain current hold in the subthreshold, transition, and strong inversion regions. A continuous model is proposed for the transition region, using a scheme that ensures that both the current and conductance are continuous and will not cause convergence problems for circuit simulation applications. All of the modeled parameters are taken from experimentally measured I-V characteristics and preserve physical meaning. Comparisons between the measured and modeled I-V characteristics show excellent agreement for a wide range of channel widths and biases. The model is well suited for circuit simulation in SPICE     

PV module characterization using Q-Rdecomposition based on the least square method

The determination of solar cell parameters (I-V characteristic) from experimental data was achieved by using the Q -R decomposition technique based on the least squares method, where all data points were considered. The algorithm used a three-parameter equation transformed from the original cell equation of five parameters. This method could be used to analyze the I-V characteristics of photovoltaic (PV) modules of various technologies under the natural conditions of implementation, and to help to establish the best sizing of a PV system and the best adaptation of a PV system to its environment     

SPICE macro model for the simulation of zener diodeI-V characteristics

The problems encountered when using the existing SPICE diode model to represent the I-V characteristics of a Zener diode in the reverse region are examined. A Zener diode macro model that has accurate I-V simulation characteristics and can be easily constructed using SPICE-provided primitives is presented. The static I-V characteristics and temperature response of the diode are reviewed. The performance of the model is discussed, and its main enhancements as compared to the SPICE model are identified     

A new method of determination of the I-Vcharacteristics of negative differential conductance devices

A method for mapping the complete I-V characteristic of a negative differential conductance (NDC) device has been investigated. This method employs the measurable positive differential conductance (PDC) portions of the DC I-V curve together with the measured conductances at a fixed DC bias voltage in the PDC region with different RF signal levels using a standard semiconductor analyzer. The NDC regime of the I-V curve is numerically constructed from the measured conductances at a fixed DC bias voltage in the PDC region with different signal levels using a large-signal nonlinear-circuit analysis     

Input I-V and sampling time characteristics ofthe ACT device

The input I-V and sampling-time characteristics of the acoustic charge transport (ACT) device are presented for ohmic-contact charge injection and Schottky-gate-modulated charge injection. A computationally efficient analysis technique is developed to calculate the I-V and sampling-time data from two-dimensional potential and carrier-density distributions. Device physics and architecture are incorporated into the analysis through a numerical charge-injection model which is used to compute the potential and carrier-density distributions. Theoretical results are presented to demonstrate the charge injection characteristic of some typical device structures. The effects that the injection method, the epitaxial layer structure and the acoustic wave amplitude have on device performances are discussed. The physical basis of the analysis enables it to be used to study several other design parameters. Experimental measurements of a device I-V and input transconductance show good agreement with calculated data. This analysis technique provides a means of assessing the performance potential of new device designs     

Electrical transport properties of crystalline siliconcarbide/silicon heterojunctions

The electrical transport properties of β-SiC/Si heterojunctions were investigated using current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The heterojunctions were fabricated by growing n-type crystalline β-SiC films on p-type Si substrates by chemical vapor deposition (CVD). The I-V data measured at various temperatures indicate that at relatively high current, the heterojunction forward current is dominated by thermionic emission of carriers and can be expressed as exp(-qV_bi/kT ) exp(V/ηkT), where V_bi is the built-in voltage of the heterojunction and η(=1.3) is a constant independent of voltage and temperature. At lower current, defect-assisted multitunneling current dominates. The effective density of states and the density-of-states effective mass of electrons in the conduction band of SiC are estimated to be 1.7×10²¹ cm ^-3 and 0.78m₀, respectively. This study indicates that the β-SiC/Si heterojunction is a promising system for heterojunction (HJ) devices such as SiC-emitter heterojunction bipolar transistors (HBTs)     

Nonlinear GaAs MESFET modeling using pulsed gate measurements

The effects of traps in GaAs MESFETs are studied using a pulsed gate measurement system. The devices are pulsed into the active region for a short period (typically 1 μs) and are held in the cutoff region for the rest of a 1-ms period. While the devices are on, the drain current is sampled and a series of pulsed gate I-V curves are obtained. The drain current obtained under the pulsed gate conditions for a given V_GS and V_DS gives a better representation of the instantaneous current for a corresponding V_gs and V_ds in the microwave cycle because of the effects of traps. The static and pulsed gate curves were used in a nonlinear time-domain model to predict harmonic current. The results showed that analysis using pulsed gate curves yielded better predictions of harmonic distortion than analysis based on conventional state I-V curves under large-signal conditions     

A new method of determination of the I-Vcharacteristics of negative differential conductance devices bymicrowave reflection coefficient measurements

A technique to map out all of the I-V characteristics of negative differential conductance (NDC) devices is described. This method uses the DC measurable positive conductance portions of the I-V curve together with the measured microwave reflection coefficients at different RF signal levels and fixed DC bias voltage. The advantages of the method for high NDC devices are pointed out in a stability analysis. The complete I-V curve of a tunnel diode has been obtained with an accuracy within 5% in a proof-of-principal test of this method     

A new I-V model for short gate-length MESFET's

An I-V model for short gate-length MESFETs operated in the turn-on region is proposed, in which the two-dimensional potential distributions contributed by the depletion-layer charges under the gate and in the ungated region are separately obtained by conventional 1-D approximation and the Green's function solution technique. Moreover, the bias-dependent parasitic resistances due to the modulation of the depletion layer in the ungated region for non-self-alignment MESFETs are also taken into account in the developed I-V model. It is shown that good agreement is obtained between the I-V model and the results of 2-D numerical analysis. Moreover, comparisons between the proposed analytical model and the experimental data are made, and excellent agreement is obtained     

Surface-charge properties of fluorine-doped lead borosilicate glass

Surface-charge configurations, together with stability under bias-temperature (BT) stress, for F-doped and Na-doped lead borosilicate glass were investigated by using C-V and I- V measurements on metal-glass-silicon capacitors and on diodes passivated with the glass. The C-V characteristics showed an increase in negative charge for F doping and in positive charge for Na doping. Alkali impurities in the glass mainly controlled the surface-charge shift during BT, but additional changes, similar to those for Na doping but reversing the sign of the charge, took place by F doping. The leakage current decrease in the diode passivated with F-doped glass, which contradicts the results of C-V measurement, may be due to the education of the generation current by the interaction between the silicon surface and F^- ions     

The electrical characteristics of bulk unipolar camel diodes inpre-amorphized silicon

Barrier heights derived from the measured forward I-V characteristics are consistent with barrier heights calculated using doping profiles determined by secondary ion mass spectroscopy (SIMS). Reverse-bias I-V characteristics show excessive barrier pull-down, which is explained by the presence of excess donors at the original amorphous-single-crystal interface. The existence of these donors has been confirmed by C-V profiling. A reduction in excess donor density by plasma hydrogenation has led to a corresponding reduction in the reverse-bias barrier pull-down. These camel diodes have reverse-bias characteristics superior to those of diodes fabricated in single-crystal silicon     

A new technique for determining the generation lifetime profile inthin semiconductor films with application to silicon-on-insulator (SOI)substrates

A differential technique which uses reverse-biased current-voltage (I-V) and capacitance-voltage (C-V) measurements on a p-n junction or a Schottky barrier diode for determining the generation lifetime profile in thin semiconductor films is discussed. It is shown that the bias-independent current can be eliminated by this differential technique. Furthermore, any error caused by field-enhanced current can be estimated. This method has been used to determine the generation lifetime profile in thin silicon epitaxial film grown on SIMOX substrates     

DC I-V characteristics of field emitter triodes

A simple model that is applicable to Spindt-type emitter triodes is presented. Experimentally, it has been observed that the gate current at zero collector voltage follows the same Fowler-Nordheim law as the collector current at high collector voltage, and that for low emission current densities, the sum of gate and collector currents is constant for any collector voltage and is given by the Fowler-Nordheim current I_FN. Based on these observations, a simple model has been developed to calculate the I-V characteristics of a triode. By measuring the Fowler-Nordheim emission, emission area and field enhancement can be obtained assuming a value for the barrier height. Incorporating the gate current, the collector current can be calculated from I_c=I_FN-I_g as a function of collector voltage. The model's accuracy is best at low current density. At higher emission currents, deviations occur at low collector voltages because the constancy of gate and collector currents is violated     

Temperature dependence of common-emitter I-V andcollector breakdown voltage characteristics in AlGaAs/GaAs andAlInAs/GaInAs HBT's grown by MBE

Temperature-dependent measurements from 25 to 125°C have been made of the DC I-V characteristics of HBTs with GaAs and In_0.53Ga_0.47As collector regions. It was found that the GaAs HBTs have very low output conductance and high collector breakdown voltage BV_CEO>10 V at 25°C, which increases with temperature. In striking contrast, the In_0.53Ga_0.47As HBTs have very high output conductance and low BV_CEO~2.5 V at 25°C, which actually decreases with temperature. This different behavior is explained by the >10⁴ higher collector leakage current, I_CO, in In_0.53Ga_0.47As compared to GaAs due to bandgap differences. It is also shown that device self-heating plays a role in the I-V characteristics     

Silicon-carbide high-voltage (400 V) Schottky barrier diodes

The authors describe the fabrication and characteristics of the first high-voltage (400-V) silicon-carbide (6H-SiC) Schottky barrier diodes. Measurements of the forward I-V characteristics of these diodes demonstrate a low forward voltage drop of ~1.1 V at an on-state current density of 100 A/cm² for a temperature range of 25 to 200°C. The reverse I-V characteristics of these devices exhibit a sharp breakdown, with breakdown voltages exceeding 400 V at 25°C. In addition, these diodes are shown to have superior reverse recovery characteristics when compared with high-speed silicon P-i-N rectifiers     

Heterojunction diodes formed using thin-film C containingpolycrystalline diamond and Si

Diodelike I-V characteristics measured in Al/C/Si structures formed by depositing thin C films onto Si substrates from a CH₄/Ar plasma are discussed. The films, which contain polycrystalline diamond grains, are 500-1000 A thick. It is shown that the true I-V characteristics can be measured only after removing the fixed interface charge at the metal-C interface. By taking the C to be an intrinsic polycrystalline semiconductor, it is possible to treat the diode characteristics as arising from the presence of a C/Si heterojunction