Gijs Bosman

Quantum 1/f noise associated with ionized impurity scattering and electron-phonon scattering in condensed matter

Abstract Scattering of charged particles is accompanied by the emission of soft photons. Handels theory of 1/f noise, based on the infrared quasi-divergent coupling of the system to the electromagnetic field, indicates that the current associated with a beam of scattered particles will exhibit 1/f noise. His derivation is valid in a vacuum. Here we extend his results and obtain the fluctuation spectrum for the fluctuations in cross-section and for the scattering rates w kk′ in k-space, using the Born approximation. Next we consider mobility fluctuations due to these scattering rates, employing the relaxation time solutions of the Boltzmann transport equation, valid in non-degenerate semiconductors. Explicit results are obtained for the mobility-fluctuation noise caused by ionized impurity scattering, acoustic phonon scattering, optical phonon scattering, polar optical phonon scattering, and intervalley scattering. We derive Hooges law, and the Hooge parameters for the above-mentioned processes are obtai...

Visible light emission from heavily doped porous silicon homojunction pn diodes

We observed visible light emission with a peak wavelength of 640 nm from forward biased, heavily doped porous silicon homojunction pn diodes. The light emission is attributed to electron‐hole recombination across the direct band gap of the monocrystalline quantum wires which make up the porous silicon junction layers.

Presence of mobility-fluctuation 1f noise identified in silicon P+NP transistors

The magnitude and location of mobility-fluctuation 1f noise sources have been identified by means of biasing a PNP transistor in a common emitter configuration with first a high and then a low source resistance. Comparison of the two noise spectra at the same base currents shows the low source resistor bias isolates the collector noise sources, and the high source rsolates base noise sources. The magnitude of the observed collector 1f noise gives an α − 2 × 10−6 from Kleinpennings mobility-fluctuation theory. The base 1f noise gives an α ∼- 10−7 due to an impurity mobility reduction factor of about 100.

Low frequency noise measurements as a tool to analyze deep-level impurities in semiconductor devices

Abstract An analysis method to extract the pertinent trap parameters of impurities, i.e. energy level, trap density, spin degeneracy and capture cross section, from low-frequency noise measurements is discussed. This method, which is based on the model of traps interacting independently with the conduction band, is applied to generation recombination noise spectra measured on planar n + - n - n + Si resistors as a function of temperature, and the trap parameters are obtained. Since the analysis method makes use of some assumptions, its validity is verified by using obtained trap parameters as input for an exact multilevel computer simulation program. This program generates zero-frequency plateau levels and characteristic times in good agreement with the measured data, indicating that the assumptions were warranted. In addition, an alternative explanation of the noise data in terms of a double-donor model is studied. However, no conclusive evidence was found in favor of either one of the two models since both models explained the experimental findings within the experimental errors.

Transit-Time Effects in the Noise of Schottky-Barrier Diodes

Room-temperature noise measurements at 2.2, 12, and 97.5 GHz were performed on commercial silicon Schottky-barrier diodes and are shown to agree with the model presented in this work. This model is an extension of earlier work by van der Ziel on infrared detection in Schottky-barrier diodes. In the theoretical analysis, the electrons participating in the charge-transport process across the barrier are subdivided into four groups based on their initial velocity. The contribution of each group to the device conductance, susceptance, and current spectral intensity was incorporated including the effects of the transit time. By taking each of these effects into account, an accurate model which applies over a wide range of bias and frequency has been developed. Although the emphasis of this model has been on the high-frequency performance, the model also gives the correct results in the low-frequency limit.

Noise model of gate-leakage current in ultrathin oxide MOSFETs

A physics-based analytical model of the gate-leakage current noise in ultrathin gate oxide MOSFETs is presented. The noise model is based on an inelastic trap-assisted tunneling transport. We employ the barrier height fluctuation model and the Lorentzian-modulated shot noise of the gate-leakage current stemming from the two-dimensional electron gas channel to explain the excess noise behavior. The excess noise can be interpreted as the sum of 1/f/sup /spl gamma// noise and the Lorentzian-modulated shot noise. Trap-related processes are the most likely cause of excess current noise because slow traps in the oxide can result in low-frequency dissipation in the conductance of oxides and fast traps can produce the Lorentzian-modulated shot noise associated with generation-recombination process at higher frequencies. In order to verify the proposed noise model, the simulation results are compared with experimental data, and excellent agreement is observed.

Simulation of oxide trapping noise in submicron n-channel MOSFETs

Carrier trapping via tunneling into the gate oxide was implemented into a partial differential equation-based semiconductor device simulator to analyze the 1/f-like noise in silicon MOSFETs. Local noise sources are calculated using the carrier tunneling rates between trap centers in the oxide and those at the interface. Using the Greens transfer function approach, noise contributions from each node in the oxide mesh to the overall noise at the specified contact terminals are simulated. Unlike traditional 1/f noise analyses in MOSFETs, the simulator is capable of simulating noise for a wide range of bias voltages and device structures. The simulation results show that for an uniformly doped channel, the region in the oxide above the pinch-off point in saturation is most critical for low frequency noise generation while for a graded channel device the source side of the gate oxide region becomes important. By comparing the simulation results with the measured noise data, the oxide defect density in the noise producing regions can be profiled.

Model and analysis of gate leakage current in ultrathin nitrided oxide MOSFETs

An analytical model of the gate leakage current in ultrathin gate nitrided oxide MOSFETs is presented. This model is based on an inelastic trap-assisted tunneling (ITAT) mechanism combined with a semi-empirical gate leakage current formulation. The tunneling-in and tunneling-out current are calculated by modifying the expression of the direct tunneling current model of BSIM. For a microscopic interpretation of the ITAT process, resonant tunneling (RT) through the oxide barrier containing potential wells associated with the localized states is proposed. We employ a quantum-mechanical model to treat electronic transitions within the trap potential well. The ITAT current model is then quantitatively consistent with the summation of the resonant tunneling current components of resonant energy levels. The 1/f noise observed in the gate leakage current implies the existence of slow processes with long relaxation times in the oxide barrier. In order to verify the proposed ITAT current model, an accurate method for determining the device parameters is necessary. The oxide thickness and the interface trap density of the gate oxide in the 20-30 /spl Aring/ thickness range are evaluated by the quasi-static capacitance-voltage (C-V) method, dealing especially with quantum-mechanical and polysilicon effects.

Two-dimensional semiconductor device simulation of trap-assisted generation-recombination noise under periodic large-signal conditions and its use for developing cyclostationary circuit simulation models

The simulation of generation-recombination (GR) noise under periodic large-signal conditions in a partial differential equation-based silicon device simulator is presented. Using the impedance-field method with cyclostationary noise sources, it is possible to simulate the self- and cross-spectral densities between sidebands of a periodic large-signal stimulus. Such information is needed to develop noise correlation matrices for use with a circuit simulator. Examples are provided which demonstrate known results for shot noise in bipolar junction transistors. Additional results demonstrate the upconversion of low-frequency GR noise for microscopically cyclostationary noise sources and provide evidence for applying the modulated stationary noise model for low-frequency noise when there is a nearly quadratic current dependence.

An analytical model for 1/f noise in polycrystalline silicon thin films

Noise calculations based on Hooges empirical mobility fluctuation model are presented for mobility fluctuations occurring in the quasi-neutral and the depletion-barrier regions of low to moderately doped polycrystalline silicon resistors. Comparing the theoretical predictions with the experimental results, it is concluded from the bias dependence and the magnitude of the noise density that the 1/f noise in polysilicon is depletion-region dominant. The limiting role of grain boundaries, the noise correlation between depletion regions on both sides of a grain boundary, and a noise source weight function are taken into account. The Hooge parameter found from the model and data is 1.45*10/sup -3/. >