Depletion region

About: Depletion region is a research topic. Over the lifetime, 9393 publications have been published within this topic receiving 145633 citations.

Reducing the switching time of semiconductor devices by neutron irradiation

Abstract: A method of reducing the switching time of certain semiconductor devices and particularly gain-operated semiconductor devices. The depth of maximum defect generation in a given type of semiconductor devices having a block PN junction is determined on irradiation with a given radiation source emitting particles with molecular weight of at least one (1), preferably protons or alpha particles; and the energy level of the radiation source adjusted to provide the depth of maximum defect generation adjacent a blocking PN junction of the type of semiconductor device. At least one semiconductor device of said given type of semiconductor device is positioned with a major surface thereof to be exposed to the adjusted radiation source, and thereafter irradiated with the adjusted radiation source to a given dosage level to reduce the switching time of the semiconductor device. Preferably, the semiconductor device is positioned and the energy level of the radiation source adjusted to irradiate through the major surface of the device closer the higher impurity region adjoining the blocking PN junction, and to provide the maximum defect generation in said higher impurity region adjoining the blocking PN junction but spaced from the PN junction beyond a depletion region formed at the PN junction on application of a specified blocking voltage across the PN junction of the semiconductor device.

Electric and Dielectric Properties of Au/ZnS-PVA/n-Si (MPS) Structures in the Frequency Range of 10–200 kHz

Abstract: Pure polyvinyl alcohol (PVA) capped ZnS semiconductor nanocrystals were prepared by microwave-assisted method, and the optical and structural properties of the as-prepared materials were characterized by x-ray diffraction (XRD) and Ultraviolet–visible (UV-Vis) techniques. The XRD pattern shows the formation of ZnS nanocrystals, and the UV–Vis spectroscopy results show a blue shift of about 1.2 eV in its band gap due to the confinement of very small nanostructures. The concentration of donor atoms (N D), diffusion potential (V D), Fermi energy level (E F), and barrier height (ΦB (C–V)) values were obtained from the reverse bias C −2–V plots for each frequency. The voltage dependent profile of series resistance (R s) and surface states (N ss) were also obtained using admittance and low–high frequency methods, respectively. R s–V and N ss–V plots both have distinctive peaks in the depletion region due to the spatial distribution charge at the surface states. The effect of R s and interfacial layer on the C–V and G/ω–V characteristics was found remarkable at high frequencies. Therefore, the high frequency C–V and G/ω–V plots were corrected to eliminate the effect of R s. The real and imaginary parts of dielectric constant (e′ and e″) and electric modulus (M′ and M″), loss tangent (tan δ), and ac electrical conductivity (σ ac) were also obtained using C and G/ω data and it was found that these parameters are indeed strong functions of frequency and applied bias voltage. Experimental results confirmed that the N ss, R s , and interfacial layer of the MPS structure are important parameters that strongly influence both the electrical and dielectric properties. The low values of N ss (~109 eV−1 cm−2) and the value of dielectric constant (e′ = 1.3) of ZnS-PVA interfacial layer even at 10 kHz are very suitable for electronic devices when compared with the SiO2. These results confirmed that the ZnS-PVA considerably improves the performance of Au/n-Si (MS) structure and also allow it to work as a capacitor, which stores electric charges or energy.

The C–V–f and G/ω–V–f characteristics of Au/SiO2/n-Si capacitors

Abstract: Au/SiO2/n-Si metal–insulator-semiconductor (MOS) structures with thermal growth oxide layer have been fabricated. The frequency dependence of capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of these structures have been investigated taking into account the effect of the series resistance and interface states. The C–V and G/ω–V measurements have been carried out in the frequency range of 1 kHz–1 MHz at room temperature. The frequency dispersion in capacitance and conductance can be interpreted in terms of the interface states density (Nss) and series resistance values (Rs). The interface states can follow the ac signal and yield an excess capacitance especially at low frequencies. The values of measured C and G/ω decrease in depletion region with increasing frequencies especially in low frequencies due to a continuous density distribution of interface states. The C–V plots exhibit anomalous peaks due to the Nss and Rs effect. It has been experimentally found that the peak positions in the C–V plot shift towards positive voltages and the peak value of the capacitance decreases with increasing frequency. The effect of series resistance on the capacitance is found appreciable at high frequencies due to the interface state capacitance decreasing with increasing frequency. In addition, the high-frequency capacitance (Cm) and conductance (Gm/ω) values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real diode capacitance. Experimental results show that the locations of interface states between Si/SiO2 and series resistance have a significant effect on electrical characteristics of MOS structures.

A generalized simulation method for MITATT-mode operation and studies on the influence of tunnel current on IMPATT properties

Abstract: A generalized method of DC and high-frequency analysis for microwave transit time diodes in mixed tunnelling and avalanche mode, which can be applied to any type of diode structure is reported. Taking a purely field-dependent tunnel generation rate for electrons, the same is computed for holes from a simulated energy band diagram within the depletion layer of the diode. The method has been applied to a variety of Si, GaAs and InP diode structures. The results show a substantial degradation of IMPATT properties due to phase distortion caused by the tunnelling current.