Dead-space Multiplication Theory Research Articles

High gain and low excess noise InGaAs/InP avalanche photodiode with lateral impact ionization.

In this paper, modeling for a lateral impact ionization InGaAs/InP avalanche photodiode (APD) has been performed based on a device simulator, i.e., Silvaco ATLAS. Compared with traditional APDs, the lateral impact ionized APD has much higher gains as well as lower excess noise. The internal gain for our newly proposed lateral APD is over 1000-near the breakthrough voltage. In addition, the excess noise characteristic of this device is also discussed with three-dimensional dead space multiplication theory, and the calculated effective $k$k value is obviously lower than traditional InGaAs/InP APDs. Because of the high gain and low excess noise characteristics, the proposed APD can be widely applied for optical detection with high sensitivity.

On the analytical formulation of excess noise in avalanche photodiodes with dead space.

Simple, approximate formulas are developed to calculate the mean gain and excess noise factor for avalanche photodiodes using the dead-space multiplication theory in the regime of small multiplication width and high applied electric field. The accuracy of the approximation is investigated by comparing it to the exact numerical method using recursive coupled integral equations and it is found that it works for dead spaces up to 15% of the multiplication width, which is substantial. The approximation is also tested for real materials such as GaAs, InP and Si for various multiplication widths, and the results found are accurate within ∼ 15% of the actual noise, which is a significant improvement over the local-theory noise formula. The results obtained for the mean gain also confirm the recently reported relationship between experimentally determined local ionization coefficients and the enabled non-local ionization coefficients.

Non-Local Model for the Spatial Distribution of Impact Ionization Events in Avalanche Photodiodes

We report an extension of the analytical dead space multiplication theory that provides the means to theoretically determine the spatial distribution of electron and hole impact-ionization events in an arbitrarily specified heterojunction multiplication region. The model can be used to understand the role of the dead space in regularizing the locations of impact ionization. It can also be utilized to analyze, design, and optimize new generations of ultra-low noise, multistaged gain avalanche photodiodes based upon judiciously energizing and relaxing carriers to enhance electron impact ionization and suppress hole impact ionization.

Dual-Carrier High-Gain Low-Noise Superlattice Avalanche Photodiodes

In this paper, novel avalanche photodiode structures with alternate carrier multiplication nanometer regions, placed next to a wider electron multiplication region, to create dual-carrier feedback systems, are proposed. Gain and excess noise factor of these structures are calculated based on the dead space multiplication theory under uniform electric field. In addition, the equivalent impact ionization ratios are derived and compared. It is observed that the proposed structures can generate much higher gain compared with conventional pure electron multiplication structures under the same electric field without severely degrading the excess noise quality. Excess noise is further optimized with careful adjustment of thin multiplication regions' thicknesses. These high-gain structures can operate under low-bias (<; 5 V) conditions, making it possible to integrate infrared avalanche photodiodes (APDs) directly into silicon read-out circuits. In this paper, type-II mid-wavelength infrared InAs/GaSb strained layer superlattice is used for simulation. However, the concept of dual-carrier APDs, with carrier feedback to generate high gain and control of excess noise through confining impact ionization in thin layers, is general and can also be applied to other wavelength APDs with different materials and thicknesses. Type II InAs/GaSb strain layer superlattice allows for versatile band structure design leading to impact ionization coefficient engineering.

EFFECT OF MULTIPLICATION REGION MOLE FRACTION ON CHARACTERISTICS OF ALxGA1-xAS-APDS IN THE LINEAR AND GEIGER

In this paper we introduce general numerical analysis for investigation the performance of avalanche photodiodes (APD) while we change the multiplication region mole fraction. We have found that the gain, breakdown voltage, and performance factor, at a given bias voltage, increase while the excess noise factor decreases through the decreases in fraction of Al in AlxGa1−xAs-APDs. For calculation the characteristics of AlxGa1−xAs-APDs we use the dead space multiplication theory (DSMT) and width independent ionization coefficient.

Breakdown voltage in thin III–V avalanche photodiodes

The dead-space multiplication theory of Hayat and Saleh [J. Lightwave Technol. 10, 1415 (1992)], in conjunction with the multiplication-width-independent ionization-coefficient model developed by Saleh et al. [IEEE Trans. Electron Devices 47, 625 (2000)], are shown to accurately predict breakdown voltages for thin avalanche photodiodes of GaAs, InP, In0.52Al0.48As, and Al0.2Ga0.8As, over a broad range of device widths. The breakdown voltage is determined from the analytical expression for the impulse-response-function decay rate.

Impact-ionization and noise characteristics of thin III-V avalanche photodiodes

It is, by now, well known that McIntyre's localized carrier-multiplication theory cannot explain the suppression of excess noise factor observed in avalanche photodiodes (APDs) that make use of thin multiplication regions. We demonstrate that a carrier multiplication model that incorporates the effects of dead space, as developed earlier by Hayat et al. provides excellent agreement with the impact-ionization and noise characteristics of thin InP, In/sub 0.52/Al/sub 0.48/As, GaAs, and Al/sub 0.2/Ga/sub 0.8/As APDs, with multiplication regions of different widths. We outline a general technique that facilitates the calculation of ionization coefficients for carriers that have traveled a distance exceeding the dead space (enabled carriers), directly from experimental excess-noise-factor data. These coefficients depend on the electric field in exponential fashion and are independent of multiplication width, as expected on physical grounds. The procedure for obtaining the ionization coefficients is used in conjunction with the dead-space-multiplication theory (DSMT) to predict excess noise factor versus mean-gain curves that are in excellent accord with experimental data for thin III-V APDs, for all multiplication-region widths.

Dead-space-based theory correctly predicts excess noise factor for thin GaAs and AlGaAs avalanche photodiodes

The conventional McIntyre carrier multiplication theory for avalanche photodiodes (APDs) does not adequately describe the experimental results obtained from APDs with thin multiplication-regions. Using published data for thin GaAs and Al/sub 0.2/Ga/sub 0.8/As APDs, collected from multiplication-regions of different widths, we show that incorporating dead-space in the model resolves the discrepancy. The ionization coefficients of enabled carriers that have traveled the dead space are determined as functions of the electric field, within the confines of a single exponential model for each device, independent of multiplication-region width. The model parameters are determined directly from experimental data. The use of these physically based ionization coefficients in the dead-space multiplication theory, developed earlier by Hayat et al. provide excess noise factor versus mean gain curves that accord very closely with those measured for each device, regardless of multiplication-region width. It is verified that the ratio of the dead-space to the multiplication-region width increases, for a fixed mean gain, as the width is reduced. This behavior, too, is in accord with the reduction of the excess noise factor predicted by the dead-space multiplication theory.