Injection Photodiode Research Articles

Obtaining new types of compounds between silicon and cadmium sulfide

The n+CdS-nCdS-nSi+ structures were obtained and their volt-ampere characteristics at different temperatures were studied. From the dependence of the volt-ampere characteristic it is shown that the sublinear and quadratic section of these structures has a section of current growth with voltage. It is determined that the n+CdS-nCdS-nSi+structures in the current flow direction at low illumination levels work as an injection photodiode. And these structures under laser illumination with λ=0.625 μm and power P=1.2 μW/cm2 have spectral sensitivity 2042 A/W, bias voltage 10 V. At irradiation by white light with energy W=3.6-10μW∙s it has integral sensitivity ≈21 A/I’m (2310 A/W) at bias voltage U=10V.

Obtaining new types of compounds between silicon and cadmium sulfide

The n+CdS-nCdS-nSi+ structures were obtained, and their volt-ampere characteristics at different temperatures were studied. The dependence of the volt-ampere characteristic shows that the sublinear and quadratic section of these structures has a section of current growth with voltage. It is determined that the n+CdS-nCdS-nSi+ structures in the current flow direction at low illumination levels work as an injection photodiode. And these structures under laser illumination with λ=0.625 μm and power P=1.2 µW/cm2 have spectral sensitivity 2042 A/W, bias voltage 10 V. At irradiation by white light with energy W=3.6-10µW·s it has integral sensitivity ≈21 A/I'm (2310 A/W) at bias voltage U=10V.

Spin-Coating and Aerosol Spray Pyrolysis Processed Zn1-xMgxO Films for UV Detector Applications.

A series of Zn1−xMgxO thin films with x ranging from 0 to 0.8 were prepared by spin coating and aerosol spray pyrolysis deposition on Si and quartz substrates. The morphology, composition, nano-crystalline structure, and optical and vibration properties of the prepared films were studied using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and optical and Raman scattering spectroscopy. The optimum conditions of the thermal treatment of samples prepared by spin coating were determined from the point of view of film crystallinity. The content of crystalline phases in films and values of the optical band gap of these phases were determined as a function of the chemical composition. We developed heterostructure photodetectors based on the prepared films and demonstrated their operation in the injection photodiode mode at forward biases. A device design based on two Zn1−xMgxO thin films with different x values was proposed for extending the operational forward bias range and improving its responsivity, detectivity, and selectivity to UV radiation.

Фотоэлектрическое инжекционное усиление инжекционного фотодиода на основе крупноблочных пленок CdTe при освещении “примесным” светом

Фотоэлектрическое инжекционное усиление инжекционного фотодиода на основе крупноблочных пленок CdTe при освещении “примесным” светом

Injection photodiodes based on metal oxide semiconductors

Injection photodiodes based on metal oxide semiconductors

Electrophysical and Photoelectric Properties of Injection Photodiode Based on pSi–nCdS–In Structure and Influence of Ultrasonic Irradiation on them

Electrophysical and Photoelectric Properties of Injection Photodiode Based on pSi–nCdS–In Structure and Influence of Ultrasonic Irradiation on them

Ultrasonic annealing of surface states in the heterojunction of a p-Si/n-CdS/n +-CdS injection photodiode

We have studied the effect of ultrasonic processing on the electrical and photoelectric properties of a p-Si/n-CdS/n+-CdS injection photodiode. The results demonstrate that ultrasonic processing of such photodiodes reduces the density of surface states at the interface of their heterojunction as a result of defect annealing. This increases the spectral and integrated sensitivities of the photodiodes.

Injection photodiode based on a p-Si-n-CdS-n +-CdS structure

An injection photodiode with a high room-temperature rectification factor (105) is developed based on a p-Si-n-CdS-n +-CdS structure. It is shown that the light and dark current-voltage characteristics of the structure have identical features. It is found that the mode of “long” diodes is implemented in the structure at current densities of I = 10−2−5 × 10−4 A/cm2; in this case, the integral (S int) and spectral (S λ) sensitivities sharply increase. It is shown that S int = 2.8 × 104 A/lm (3 × 106 A/W) for an illuminance of E = 0.1 lux and S λ = 2.3 × 104 A/W under laser irradiation with λ = 625 nm and a power of P = 10 μW/cm2 at a bias voltage of V = 20 V. It is shown that the mechanism of photocurrent amplification is predominantly associated with ambipolar carrier-mobility modulation.

Mechanism of charge transfer in injection photodiodes based on the In-n +-CdS-n-CdS x Te1 − x -p-Zn x Cd1 − x Te-Mo structure

Photosensitive In-n+-CdS-n-CdSxTe1 − x-p-ZnxCd1 − xTe-Mo film structures based on II–VI semiconductors and operating in the wavelength range λ = 0.490–0.855 μm have been fabricated. These structures in the forward current direction at high bias voltages operate as injection photodiodes and exhibit a high integrated sensitivity Sint ≈ 700 A/lm (14500 A/W) at room temperature. It has been found that, in the fabricated structures at low illuminance levels and low forward bias voltages (0.05–0.50 V), the diffusion and drift fluxes of nonequilibrium charge carriers are directed toward each other. This effect leads to the sign reversal of the photocurrent, which makes it possible on the basis of these structures to create selective photodetectors with injection properties. In the reverse direction of the photocurrent, these structures also operate in the mode of internal amplification of the primary photocurrent, but the integrated sensitivity in this mode is considerably less than that in the forward current direction.

Injection photodiode based on an n-CdS/p-CdTe heterostructure

The possibility of developing injection photodiodes with a tunable/reconfigurable? photosensitivity spectrum in the spectral range of 500–800 nm based on an n-CdS/p-CdTe heterostructure is shown. It is established that such a structure in the short-wavelength region λ = 500 nm has the highest spectral sensitivity Sλ ≈ 3 A/W in the forward direction at a bias voltage of V = +120 mV and Sλ ≈ 2 A/W in the reverse direction at a bias voltage of V = −120 mV. The integrated sensitivity of the device is Sint = 2 400 A/lm under illumination with white light E = 3 × 10−2 lx, at a bias voltage of V = +4.6 V, and temperature of T = 293 K. Upon illumination with the monochromatic light of an LG-75 laser with the wavelength λ = 625 nm, Sint = −1400 A/W (illumination power P = 18 × 10−6 W/cm2, bias voltage V = +4.6 V, and temperature T = 293 K). High values of Sλ and Sint provide the highly efficient transformation of light energy into electrical energy at low illumination levels (P < 18 × 10−6 W/cm2).

Mechanism of current transport in Schottky barrier diodes based on coarse-grained CdTe films

The possibility of fabricating a Schottky barrier on Al-p-CdTe structures with the lowest density of surface states has been demonstrated and confirmed by the results obtained from the capacitance-voltage and photoelectric measurements of the potential barrier height. It has been established that, at different forward bias voltages, there are different exponential dependences of the electric current on the voltage, which are related to the changes in kinetic parameters of the base of the Al-p-CdTe-Mo structure. It has been shown that the Al-p-CdTe-Mo structure at a forward current and high illumination levels operates as an injection photodiode. This injection photodiode has a high current sensitivity. When the current is switched on in the reverse direction, after the complete coverage of the base of the structure by the space charge, electrons responsible for the charge transfer mechanism and noise characteristics of the structure are injected from the rear contact.

Injection photodiode based on p-CdTe film

Photosensitive large-block p-type cadmium telluride (p-CdTe) film with a resistivity of ρ ≈ 106−107 Ω cm has been used to create an Al-p-CdTe-Mo structure with a Schottky barrier, which exhibits the properties of an injection photodiode. Being switched in the forward current passage direction (with “+” on the Mo contact) at high illumination levels, the proposed structure exhibits a responsivity of Sλ ≈ 2.6 A/W at a wavelength of λ = 0.625 μm, which is about five times the spectral response of the ideal photodetector for this wavelength range.

Some features of photocurrent generation in single- and multibarrier photodiode structures

In contrast to single barrier photodiode structures, multibarrier ones exhibit the effect of increasing the number of photogenerated carriers in the entire range of operating voltages, whereas the photocurrent generation in avalanche and injection photodiodes is characterized by the threshold behavior and is associated with changes in the dark carrier density. The suggested interpretation of the effect of internal photoelectric amplification will make it possible to estimate experimental current or voltage gains and detect photoelectric amplification in photodiode structures irrespective of their type.

Injection photodiodes based on low-resistivity ZnS single crystals

Results of an experimental study of Ni-n-n+-In photodiode structures fabricated from a low-resistivity ZnS:Al crystal (n+-region) are reported. The high-resistivity compensated n-type layer is produced by thermal diffusion of silver. The photodiodes exhibit an injection amplification of the photocurrent under a forward bias of 1–10 V. The dependence of the currents through the diodes on the thickness of the n-type layer in the dark and under UV irradiation is determined. The photosensitivity is at a maximum in the fundamental absorption range in a narrow spectral band.

Photophysical characteristics of microlayer photodiode pAlGaInAs(Zn)-nGaAs-Au structures

The photoelectric characteristics of photodiode pAlGaInAs(Zn)-nGaAs-Au structures have been investigated. It has been established experimentally that an internal photoelectric amplification arises in these structures when the nGaAs-Au potential barrier is connected in opposition to the (p(Al0.08Ga0.82)0.9In0.1As-nGaAs) heterojunction. The p(Al0.08Ga0.82)0.9In0.1As-nGaAs-Au structure operates as an injection photodiode when the p-n junction operates in the forward-bias regime and as a photodiode when this junction operates in the reversebias regime. The influence of the depletion regions of the base zone containing deep impurity centers on the photosensitivity and the spectral range of the indicated structures has been investigated.