A comparison of avalanche breakdown probabilities in semiconductor materials

Abstract

Using a hard dead space impact ionization model, the dependence of breakdown probabilities on overbias ratio in single photon avalanche diodes is investigated theoretically in a variety of semiconductor materials for the simple case of constant electric field, that is, in a p⁺-i-n⁺ diode structure. By using avalanche widths of 2 μm, the effects of dead space are minimized so that the breakdown probability results are determined primarily by the enabled ionization coefficients of the materials. The results illustrate how the slope of breakdown probability with overbias ratio is affected by the enabled ionization coefficients ratio and by the field dependences of ionization coefficients, which should be taken into account when choosing semiconductor materials for single photon avalanche diodes.     

Microchannel avalanche photodiode with broad linearity range

Design and operation principles of a new microchannel avalanche photodiode with an avalanche multiplication coefficient of up to 10⁵ and a linearity range expanded by an order of magnitude compared to the existing analogs are described. A distinctive feature of the new device design is that the forward-biased p_n junctions (playing the role of individual quenching resistors) are situated under each pixel. This circumstance ensures an increase in the density of multiplication channels up to 40000 mm-2 at a 100% sensitive device area.     

Charge Carrier Transport and Deep Levels Recharge in Avalanche S-Diodes Based on GaAs

Carrier transport and deep-level recharging in semiconductor avalanche S-diode structures have been investigated. Gallium-arsenide n⁺–π–ν–n structures with the diffusion distribution of deep iron acceptors have been studied. It has been found by solving the continuity and Poisson equations with the use of a commercial software that the electron injection affects the avalanche breakdown voltage and the spacecharge region broadens due to capture of avalanche holes on negative iron ions in the π-region. It is demonstrated by comparing the results of numerical calculation with the experimental data that the S-shaped I–V characteristic of the diffusion avalanche S-diodes cannot be explained within the previously proposed mechanism of capture of avalanche holes on the deep iron levels.     

Hypersensitive avalanche photodiode with surface transport of charge carriers

The principles of design and operation of a new avalanche photodiode structure are considered. The photodiode, comprises a silicon substrate, a semitransparent titanium gate separated from semiconductor by an insulating layer, and a drain electrode ensuring the surface transport of multiplicated charge carriers along the semiconductor—insulator interface. It is shown that multielement avalanche photodiode structures can be created, including charge-coupled-device matrices with the intrinsic photosignal gain above 10⁴.     

Dielectric breakdown study of thin La2O3 films

The dielectric breakdown in La₂O₃ films of thickness 40–400 Å incorporated in capacitors is reported. The experimental results were analysed in the light of Forlani and Minnaja's theory of ionization avalanche breakdown. The dielectric breakdown strength was found to be a power function of thickness, varying as d^?0.66, in essential agreement with the theory of Forlani and Minnaja. Furthermore, these films are amorphous and have high breakdown fields (about 10 MV cm^?1).     

Single p-type/intrinsic/n-type silicon nanowires as nanoscale avalanche photodetectors

We report the controlled synthesis of axial modulation-doped p-type/intrinsic/n-type (p-i-n) silicon nanowires with uniform diameters and single-crystal structures. The p-i-n nanowires were grown in three sequential steps: in the presence of diborane for the p-type region, in the absence of chemical dopant sources for the middle segment, and in the presence of phosphine for the n-type region. The p-i-n nanowires were structurally characterized by transmission electron microscopy, and the spatially resolved electrical properties of individual nanowires were determined by electrostatic force and scanning gate microscopies. Temperature-dependent current-voltage measurements recorded from individual p-i-n devices show an increase in the breakdown voltage with temperature, characteristic of band-to-band impact ionization, or avalanche breakdown. Spatially resolved photocurrent measurements show that the largest photocurrent is generated at the intrinsic region located between the electrode contacts, with multiplication factors in excess of ca. 30, and demonstrate that single p-i-n nanowires function as avalanche photodiodes. Electron- and hole-initiated avalanche gain measurements performed by localized photoexcitation of the p-type and n-type regions yield multiplication factors of ca. 100 and 20, respectively. These results demonstrate the significant potential of single p-i-n nanowires as nanoscale avalanche photodetectors and open possible opportunities for studying impact ionization of electrons and holes within quasi-one-dimensional semiconductor systems.     

A fiber-optically triggered avalanche transistor

A silicon bipolar transistor operating in the avalanche region was optically triggered into secondary breakdown. This transistor has been given the name fiber-optically triggered avalanche transistor (FOTAT). The FOTAT acts as an optical power discriminator. That is, secondary breakdown occurs when the triggering optical power exceeds the triggering threshold of the FOTAT. This secondary breakdown is seen as a negative resistance between the collector and emitter. High voltage (>100 V) nanosecond transition duration pulses are generated using this negative resistance     

Lucky-drift model for impact ionization in amorphous semiconductors

A lucky-drift model for impact ionization has been recently successfully used to account for avalanche phenomenon in amorphous selenium (a-Se). We extend the calculations in order to compare the effect in a-Se with possible impact ionization phenomenon in another prototype amorphous semiconductor: hydrogenated amorphous silicon (a-Si:H). The results suggest that the higher phonon energy in a-Si:H as compared to a-Se shifts the threshold field for impact ionization in a-Si:H to essentially higher fields than those needed for avalanche multiplication in a-Se. Furthermore, it has been recently suggested that impact ionization is a precursor of the switching effect in the phase-change-memory materials (Ge₂Sb₂Te₅). We apply the lucky-drift model to Ge₂Sb₂Te₅ and show that it is capable to account for the magnitude of the electric field necessary to launch the electronic switching in this material.     

A microchannel avalanche photodiode with a fast recovery time of parameters

The design and operation principle of a novel microchannel avalanche photodiode with the short recovery time of parameters are considered in this Letter. A distinctive feature of the new device is that at the operating potential on it, the n ⁺ regions (pixels) deeply submerged into the epitaxial layer with p-type conductivity are completely depleted; thus, the possibility of accumulation of multiplied charge carriers in them is carried out. This enables attaining the recovery time of pixels in the device of ~50 ns at photocurrent amplification factor equal to 250.     

Avalanche Carrier Multiplication in Multilayer Black Phosphorus and Avalanche Photodetector

A highly sensitive avalanche photodetector (APD) is fabricated by utilizing the avalanche multiplication mechanism in black phosphorus (BP), where a strong avalanche multiplication of electron–hole pairs is observed. Owing to the small bandgap (0.33 eV) of the multilayer BP, the carrier multiplication occurs at a significantly lower electric field than those of other 2D semiconductor materials. In order to further enhance the quantum efficiency and increase the signal‐to‐noise (S/N) ratio, Au nanoparticles (NPs) are integrated on the BP surface, which improves the light absorption by plasmonic effects. The BP–Au‐NPs structure effectively reduces both dark current (≈10 times lower) and onset of avalanche electric field, leading to higher carrier multiplication, photogain, quantum efficiency, and S/N ratio. For the BP–Au‐NPs APD, it is obtained that the external quantum efficiency (EQE) is 382 and the responsivity is 160 A W^‐1 at an electric field of 5 kV cm^‐1 (V_d ≈ 3.5 V, note that for the BP APD, EQE = 4.77 and responsivity = 2 A W^‐1 obtained at the same electric field). The significantly increased performance of the BP APD is promising for low‐power‐consumption, high‐sensitivity, and low‐noise photodevice applications, which can enable high‐performance optical communication and imaging systems.     

Experimental Observation of Delayed Impact-Ionization Avalanche Breakdown in Semiconductor Structures without p–n Junctions

We have experimentally studied the dynamics of impact-ionization switching in semiconductor structures without p–n junctions when subnanosecond high-voltage pulses are applied. Silicon n⁺–n–n⁺ type structures and volume ZnSe samples with planar ohmic contacts exhibit reversible avalanche switching to the conducting state within about 200 ps, which resembles the well-known phenomenon of delayed avalanche breakdown in reverse-biased p⁺–n–n⁺ diode structures. Experimental data are compared to the results of numerical simulations.

     

Investigation of the thermal stability of picosecond gallium arsenide dynistor switches

The operation of GaAs n⁺-p-i-n ⁰-p ⁺ dynistor structures has been demonstrated experimentally under conditions of reversible avalanche breakdown at temperatures up to 200 °C with switching times remaining under 140 ps. A numerical simulation refined the influence of various parameters of the semiconductor on the temperature dependence of the switching characteristics. Pis’ma Zh. Tekh. Fiz. 24, 73–78 (August 12, 1998)     

On the mechanism of electric breakdown under low-pressure discharge in helium

It us shown that the left branch of the Paschen curve is determined by the gas phase breakdown, which is caused by the electron avalanche at pD ≥ (pD)_e and by the gas ionization by fast positive ions at pD < (pD)_e. The (pD)_e threshold value is evaluated, and it is established that the E/p ratio is the main parameter determining the gas breakdown.     

Oxide defect densities and related breakdown lifetimes

On the basis of the Shatzkes-Av-Ron model of time-dependent dielectric breakdown in SiO₂, we propose a method to determine defect densities of thin SiO₂ films and related breakdown lifetimes from voltage ramp tests on metal/oxide/ semiconductor capacitors with different electrode areas. The field-dependent defect density of our silicon oxides (SiO₂) 6.4×10⁻⁸m thick was found to increase exponentially with the breakdown field. This exponential relation allows a lower bound to be determined for the defect-related oxide breakdown lifetime at low breakdown fields. Oxide aging effects were found to decelerate defect-related time-dependent dielectric breakdown.     

AlGaN solar-blind APD with low breakdown voltage

A p-i-i-n type AlGaN heterostructure avalanche photodiodes (APDs) is proposed to decrease the avalanche breakdown voltage and to realize higher gain by using high-Al-content AlGaN layer as multiplication layer and low-Al-content AlGaN layer as absorption layer. The calculated results show that the designed APD can significantly reduce the breakdown voltage by almost 30%, and about sevenfold increase of maximum gain compared to the conventional AlGaN APD. The noise in designed APD is also less than that in conventional APD due to its low dark current at the breakdown voltage point. Moreover, the one-dimensional (1D) dual-periodic photonic crystal (PC) with anti-reflection coating filter is designed to achieve the solar-blind characteristic and cutoff wavelength of 282 nm is obtained.     

Optical amplification in a planar multichannel Mach-Zehnder interferometer based on metal-semiconductor-metal structures

This paper describes a new optoelectronic device—an optical transistor that provides power amplification of output visible radiation. The optical transistor is structurally based on a metallized semiconductor plate with a microchannel gap in the form of a planar Mach-Zehnder interferometer. A device of the light-light type is controlled by modulating the refractive index in one arm of the interferometer. Pis’ma Zh. Tekh. Fiz. 24, 17–21 (January 26, 1998)     

A.C. electrical breakdown in thin magnesium oxide films

A systematic study of a.c. breakdown in magnesium oxide films of thickness 40–200 Å fabricated into capacitors is reported. It is found that the breakdown strength is a power function of the thickness d, varying as d^?0.23, as predicted by the theory of Forlani and Minnaja based on the ionization avalanche mechanism.     

Transport of Electrons on Liquid Helium Across a Tunable Potential Barrier in a Point Contact-like Geometry

We present transport measurements of electrons bound to the surface of superfluid ⁴He in a microchannel of width 10 μm. A set of electrodes 2 μm beneath the helium surface, fabricated in a split-gate configuration using electron beam lithography, are used to control the current along the microchannel as in a point contact device. As the split-gate bias V _SG is swept negative the current decreases to zero. The value of V _SG at which the current is suppressed is dependent on the AC driving voltage applied to the electron system. We explain our results using a simple model in which a potential barrier created by the split-gate electrodes must be overcome in order to allow current to flow in the microchannel. The control of electron transport in such confined geometries may offer new possibilities for mesoscopic experiments with electrons on the surface of liquid helium.     

The effect of a space charge on the operation of a high-power semiconductor current interrupter

A theoretical model has been developed that describes operation of a high-power semiconductor current interrupter (SOS diode) with allowance for the space charge formation. According to this model, as well as to the models based on the quasineutral approximation, the process of current breakage in a semiconductor structure of the SOS diode is related to the formation of strong field regions in highly doped parts of the structure. The space charge decreases the role of avalanche multiplication, thus providing for higher switching characteristics of the diode.