Properties of amorphous CdS-crystalline Si junctions
TL;DR: In this paper, an energy band diagram of the heterojunction is proposed and the results are interpreted on the basis of carrier injection from c -Si to a -CdS and the assumption that C 1 − states in a -cdS define the reverse current flow.
Abstract: Junctions between amorphous a -CdS and crystalline n -Si have been prepared. It is found that the junctions are rectifying with a coefficient k r = 10 2 −10 3 at room temperature. The temperature dependence of k r , the J - V characteristics and the spectral intensity dependence of the photocurrent have been measured. The results are interpreted on the basis of carrier injection from c -Si to a -CdS and the assumption that C 1 − states in a -CdS define the reverse current flow. An energy band diagram of the heterojunction is proposed.
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TL;DR: A simple and economical electrodeposition technique for manufacturing p,n-Si/n-Cd1−xZnxS (0≤x≤0.8) heterojunctions is presented in this paper.
5 citations
TL;DR: In this paper, the dependence of the electric and photoelectric parameters in polycrystalline heterojunctions on the x, y and heat treatment condition were investigated, and it was found that annealing the heterjunctions at T a =400 °C for τ a =5 ÷ 6 min in air leads to an improvement of the electrical and photo-electric parameters.
3 citations
TL;DR: In this paper, the density of states near the Fermi level (EFn+2kT) was determined from space-charge-limited current (SCLC) measurements on isotype a-CdSc-Si heterojunctions.
2 citations
TL;DR: In this paper, the authors proposed to use multi-quantum well structures and so called band-gap engineering, which lead to new types of APDs and PIN photo-diodes.
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TL;DR: In this paper, the soft behavior of reverse biased Schottky barrier diodes has often been difficult to interpret quantitatively, and the development of metal-silicide devices with diffused guard rings has made it possible to verify experimentally an advanced theoretical model.
Abstract: The soft behavior of reverse biased Schottky barrier diodes has often been difficult to interpret quantitatively. The development of metal-silicide devices with diffused guard rings has made it possible to verify experimentally an advanced theoretical model. Reverse characteristics can now be accurately predicted over wide ranges of current, voltage, barrier height and temperature. The theoretical description accounts for anisotropy of effective masses, scattering by optical phonons, and quantum mechanical reflection and tunneling at the metal-semiconductor interface. These considerations yield practical Richardson constants equal to 112 for electrons and 32 for holes in silicon. Absence of true saturation in the reverse characteristic is caused by an electric field dependence of the effective barrier height. In addition to the usual image-force correction, the barrier height is lowered by a newly recognized effect attributed to an electrostatic dipole layer at the metal-semiconductor interface. Experimental devices have been fabricated using RhSi, ZrSi2, and PtSi contacts, forming barriers in both n- and p-type silicon. The resulting structures have been found to be extremely stable and uniform; furthermore, the metal-semiconductor interface, produced by solid-solid chemical reaction, is believed to be free from intervening layers of oxide and other contaminants. When necessary to eliminate field-enhancement at the electrode periphery, diffused guard rings have been incorporated into the structures. Agreement between experimental data and theory is obtained over nearly five orders of magnitude in reverse bias and eleven orders of magnitude in reverse current density, usually with an rms deviation of less than 10 per cent.
293 citations
TL;DR: In this article, the electrical and photovoltaic properties of CdS-pSi cells were studied and the maximum solar conversion efficiency was shown to be about 5.5%.
Abstract: CdS-pSi and CdS-nSi junctions are prepared by vacuum evaporation of CdS on Si crystals, and their electrical and photovoltaic properties are studied. The junction prepared on hot Si substrate (substrate temperature; 150°–250°C) has properties of hetero-junction, while the one on cold substrate (50°–80°C) shows properties resembling those of Schottky barrier. CdS-pSi junctions are generally superior to CdS–nSi junctions in rectifying properties. CdS–pSi cell on cold substrate shows excellent photovoltaic effect which is comparable to that of Si solar cell. The maximum solar conversion efficiency of CdS-pSi cells is about 5.5%. Here, the CdS layer is supposed to act as a semi-transparent electrode.
34 citations
TL;DR: In this article, the validity of the Schottky theory of metal-semiconductor contacts is examined by deriving values of metallic work function for several metals on Si, CdS, GaAs, and GaP through the use of published values of barrier heights.
Abstract: The validity of the Schottky theory of metal‐semiconductor contacts is examined. This is accomplished by deriving values of metallic work function for several metals on Si, CdS, GaAs, and GaP through the use of published values of barrier heights. Values of electron affinity for the four semiconductors are also derived. Close agreement is obtained between the work function values of a given metal on different semiconductors. The derived work function values also agree in most cases with values measured recently under conditions that correspond at least approximately to the conditions existing for evaporated‐metal‐semiconductor systems. The derived values of electron affinity do not agree, however, in general with the values measured by photoelectric means. It is shown that this disagreement can be accounted for on the basis of a high density of surface states near the valence band edge of the semiconductor. In the case of GaAs, it appears that these surface states move up to the Fermi level for the high w...
32 citations
TL;DR: In this paper, an exponential trap distribution is suggested and trap density calculations agree with literature results, showing that chalcogenide glass/silicon structures behave like ideal abrupt heterojunctions.
Abstract: Sevroal properties of glass‐silicon heterojunctions have been studied as a function of glass composition. Oxide and chalcogenide glasses of both insulating and semiconducting behavior were investigated. The current‐voltage characteristic indicates space‐charge‐limited currents in the glass film regardless of composition. An exponential trap distribution is suggested and trap density calculations agree with literature results. Capacitance‐voltage measurements show that chalcogenide glass/silicon structures behave like ideal abrupt heterojunctions.
26 citations
TL;DR: In this paper, the photoconductivity of amorphous CdS films, vacuum evaporated onto cooled substrates, has been investigated and the conditions and possible reasons for the appearance of a low temperature maximum in the photoconductor temperature dependence of chalcogen rich samples have been found.
Abstract: The photoconductivity of amorphous CdS films, vacuum evaporated onto cooled substrates, has been investigated. The conditions and possible reasons for the appearance of a low temperature maximum in the photoconductivity temperature dependence of chalcogen rich samples have been found. The presence of a slow recombination centre related to the lone pair level of the one-fold coordinated negative chalcogen has been assumed. The energy necessary for both the electron (2 eV) and hole (0.4 eV) escape from this centre has been determined. Photoinduced changes in photoconductivity have been examined as well.
10 citations