A. D. van Rheenen

Influence of magnetic field on 1/f noise in GaAs resistors without surface effects

The influence on magnetic field on 1/f noise in a planar GaAs resistor grown by molecular‐beam epitaxy and without surface effects was investigated experimentally. The experimental results can be explained by the number fluctuation model but not by the mobility fluctuation model. Previously, experimental results indicating number fluctuation type of 1/f noise were mostly attributed to the surface effects associated with the particular structures used for the experiments. In our device the surface effects were diminished so that the fluctuations of the bulk current could be considered to produce the 1/f noise.

Channel length dependence of the 1/f noise in silicon metal‐oxide‐semiconductor field‐effect transistors. II. Verification of the acceleration 1/f noise process

A systematic study of the 1/f noise dependence on the channel length in p‐ and n‐channel silicon MOSFETs (metal‐oxide‐semiconductor field‐effect transistors) is presented. Devices made by the same procedure on the same chip were used. In this way, the nonuniformity of noise sources, which strongly depend on the fabrication procedure (like 1/f noise produced by surface trapping), was avoided. Hooge’s parameter αH was used as a measure of the magnitude of the 1/f noise in the device. The αH was found to vary as the square of the channel length in p MOSFETs and in the most of the n MOSFETs. Existing theories and known noise mechanisms do not explain this dependence. The incorporation of a recent theory involving the acceleration 1/f noise in semiconductors, developed by van der Ziel, explains the experimental data very well. The αH was found to be independent upon the electric field and the extraction of an effective time constant was used for comparison between theory and experiment.

1/f noise characterization of n+–p and n–i–p Hg1−xCdxTe detectors

1/f noise in n+–p and n–i–p Hg1−xCdxTe photodiodes is discussed. The n+–p diodes have coherent‐state 1/f noise or umklapp 1/f noise. The n–i–p diodes have much lower values for the Hooge parameter αH and their noise is probably due to generation–recombination‐type (trapping) 1/f noise.

Low-frequency noise in a thin active layer α-Si:H thin-film transistors

Low-frequency noise of hydrogenated-amorphous-silicon (α-Si:H) thin-film transistors (TFTs) with a thin active layer and an inverted staggered device structure operating in the conducting mode has been investigated. Pure 1/f-noise spectra were observed. The results show that the physical location of the noise in α-Si:H TFTs is different from that in crystalline metal–oxide–semiconductor field-effect transistors. The noise contributions from the channel and interface have been determined for the device operating in different modes. The 1/f noise of α-Si:H TFTs stems from the channel when the device is operated in the linear region at high gate voltages. However, the 1/f noise of α-Si:H TFTs generated at the interface becomes significant when the device is operated in the saturation region. The interface noise can be explained by the number fluctuation model (ΔN model). The channel noise can be explained by either the ΔN model or the mobility fluctuation model (Δμ model).

Low-frequency noise measurements on semiconductor devices using a probe station

We report a measurement technique that would allow the mapping of the low-frequency noise characteristics of devices across a wafer. We show that we can reliably measure the noise by using a probe station. We also show that the sensitivity of the setup is not limited by the probes. >

LOW-FREQUENCY NOISE IN SMALL INGAAS/INP P-I-N DIODES UNDER DIFFERENT BIAS AND ILLUMINATION CONDITIONS

Low‐frequency noise measurements are reported on small InGaAs/InP p‐i‐n photodiodes under different bias and illumination conditions. In the first experiment measurements were taken when the diodes were reverse biased and illuminated with incandescent light. At high frequencies the noise is shot noise and at low‐frequencies the noise has a spectrum proportional to fγ with γ=−1.0 for one set of two devices and γ=−0.8 for another set of two devices. At low‐frequencies the spectral noise intensity is proportional to the current squared. In a second experiment the diodes were forward biased (no illumination) and the spectral intensity of the low‐frequency noise was proportional to the current. Under these bias conditions it was possible to extract the parameter αH. The obtained values for this parameter are not compatible with quantum 1/f noise but do seem to coincide with values related to 1/f noise due to recombination centers.

Noise and lifetime measurements in Si p+-i-n power diodes

Abstract Noise in Si p+-i-n power diodes was measured. At low frequencies the noise was of the 1 ƒ type and at higher frequencies we observed shot noise. In the 1 ƒ noise regime, and at back bias, S I d (ƒ)/||I d | was found to be independent of the back bias; this can be explained with the help of the Hooge equation. The noise measurements then yield αH/τ, where αH is the Hooge parameter and τ the time constant associated with the hole-electron recombination process. Evaluating τ from admittance data then gives αH = (4.0 ± 0.8) × 10−3, in good agreement with the fundamental value of 4.6 × 10−3. A discussion is given of finding τ from the measurements of the (complex) h.f. device admittance.

1/f noise in double‐heterojunction AlGaAs/GaAs laser diodes on GaAs and on Si substrates

Low‐frequency electrical current noise measurements are reported on double‐heterojunction AlGaAs/GaAs laser diodes fabricated on GaAs and on Si substrates. The noise spectra show a frequency dependence proportional with f−γ with γ close to unity. The spectral intensity is proportional to the current for smaller currents ( 1 mA). The diodes built on the GaAs substrate are 50 times less noisy than the ones built on the Si substrate. This effect is attributed to the fact that the density of dislocations at the Si interface is much larger than at the GaAs substrate/device interface.

Low-frequency noise in p-channel heterostructure insulated-gate field-effect transistors (HIGFETs) at 77 K and drain current 1 mu A

Measurements of the low-frequency spectral intensity of the current fluctuations in p-channel GaAs/AlGaAs heterostructure insulated-gate field-effect transistors are discussed. The measurements were performed at 77 K and a drain current of 1 mu A. The spectra of two types of devices are compared, one grown directly on the substrate and the other embedded in an n-well. The latter type produced markedly less noise, its spectrum being almost perfect 1/f noise. The former type exhibited, in addition to the 1/f noise, a significant generation-recombination noise component in the spectrum.<<ETX>>

Generation-recombination-type 1ƒ noise in nip diodes

Abstract It is shown for pin diodes, in which the current flow is by hole-electron pair generation and (or) recombination, that the 1 ƒ γ noise is due to generation-recombination processes involving traps and (or) recombination centers and that the spectrum may be written as S I (ƒ) = α H e|I|/[ƒ γ τ] , where αH is the Hooge parameter, ϱ the electron charge, |I| the absolute current, τ the time constant associated with the pair generation and pair recombination process, ƒ the frequency and γ is the exponent of the spectrum. This is studied experimentally and the Hooge parameters of various devices are determined.