Effect of impact ionization in the InGaAs absorber on excess noise of avalanche photodiodes

In this work, Monte Carlo model is developed to investigate the avalanche characteristics of GaN and Al0.45Ga0.55N avalanche photodiodes (APDs) using random ionization path lengths incorporating dead space effect. The simulation includes the impact ionization coefficients, multiplication gain and excess noise factor for electron- and hole-initiated multiplication with a range of thin multiplication widths. The impact ionization coefficient for GaN is higher than that of Al0.45Ga0.55N. For GaN, electron dominates the impact ionization at high electric field while hole dominate at low electric field whereas Al0.45Ga0.55N has hole dominate the impact ionization at higher field while electron dominate the lower field. In GaN APDs, electron-initiated multiplication is leading the multiplication gain at thinner multiplication widths while hole-initiated multiplication leads for longer widths. However for Al0.45Ga0.55N APDs, hole-initiated multiplication leads the multiplication gain for all multiplication widths simulated. The excess noise of electron-initiated multiplication in GaN APDs increases as multiplication widths increases while the excess noise decreases as the multiplication widths increases for hole-initiated multiplication. As for Al0.45Ga0.55N APDs, the excess noise for hole-initiated multiplication increases when multiplication width increases while the electron-initiated multiplication increases with the same gradient at all multiplication widths.

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HIGH SPEED RESONANT-CAVITY InGaAs/InAlAs AVALANCHE PHOTODIODES

International Journal of High Speed Electronics and Systems ◽

10.1142/s0129156400000350 ◽

2000 ◽

Vol 10 (01) ◽

pp. 327-337

Author(s):

J. C. CAMPBELL ◽

H. NIE ◽

C. LENOX ◽

G. KINSEY ◽

P. YUAN ◽

...

Keyword(s):

High Speed ◽

Impact Ionization ◽

Avalanche Photodiodes ◽

Resonant Cavity ◽

Multiple Quantum Well ◽

Low Noise ◽

Excess Noise ◽

Multiple Quantum ◽

Gain Bandwidth ◽

Unity Gain

The evolution of long-haul optical fiber telecommunications systems to bit rates greater than 10 GB/s has created a need for avalanche photodiodes (APDs) with higher bandwidths and higher gain-bandwidth products than are currently available. It is also desirable to maintain good quantum efficiency and low excess noise. At present, the best performance (f3dB ~ 15 GHz at low gain and gain-bandwidth product ~ 150 GHz) has been achieved by AlInAs/InGaAs(P) multiple quantum well (MQW) APDs. In this paper we report a resonant-cavity InAlAs/InGaAs APD that operates near 1.55 μm. These APDs have achieved very low noise (k equivalent to 0.18) as a result of the very thin multiplication regions that were utilized. The low noise is explained in terms of a new model that accounts for the non-local nature of impact ionization. A unity-gain bandwith of 24 GHz and a gain-bandwidth-product of 290 GHz were achieved.

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Multiplication gain and excess noise factor in thin SiC avalanche photodiodes

Malaysian Journal of Fundamental and Applied Sciences ◽

10.11113/mjfas.v12n4.477 ◽

2017 ◽

Vol 12 (4) ◽

Author(s):

Heng Ah You ◽

Che Cha Sun

Keyword(s):

Breakdown Voltage ◽

Dead Space ◽

Impact Ionization ◽

Avalanche Photodiodes ◽

Monte Carlo Model ◽

Noise Factor ◽

Excess Noise ◽

Excess Noise Factor ◽

Multiplication Gain ◽

Space Effect

This work simulated the avalanche characteristics of 4H- and 6H-SiC avalanche photodiodes (APDs) at 0.1 µm, 0.2 µm and 0.3 µm avalanche widths. A Monte Carlo model with random ionization path length techniques is developed to simulate mean multiplication gain and excess noise factor in thin SiC APDs. Mean multiplication gain, breakdown voltage and excess noise factor are simulated based on the electric field dependent impact ionization coefficients with the inclusion of dead space effect. Our results show that hole-initiated impact ionization gives high multiplication gain with low excess noise factor in both devices. We observed that dead space effect is more pronounce in thin structure since it covers a significant portion of the avalanche region. In thick device structure, a high breakdown voltage is observed. A comparison between these two polytypes shows that 4H-SiC provides high multiplication gain with low excess noise factor than 6H-SiC.

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Valence band engineering of GaAsBi for low noise avalanche photodiodes

Nature Communications ◽

10.1038/s41467-021-24966-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yuchen Liu ◽

Xin Yi ◽

Nicholas J. Bailey ◽

Zhize Zhou ◽

Thomas B. O. Rockett ◽

...

Keyword(s):

Valence Band ◽

Impact Ionization ◽

Avalanche Photodiodes ◽

Low Noise ◽

Excess Noise ◽

Critical Parameters ◽

Orbit Splitting ◽

Band Engineering ◽

Useful Signal ◽

The Impact

AbstractAvalanche Photodiodes (APDs) are key semiconductor components that amplify weak optical signals via the impact ionization process, but this process’ stochastic nature introduces ‘excess’ noise, limiting the useful signal to noise ratio (or sensitivity) that is practically achievable. The APD material’s electron and hole ionization coefficients (α and β respectively) are critical parameters in this regard, with very disparate values of α and β necessary to minimize this excess noise. Here, the analysis of thirteen complementary p-i-n/n-i-p diodes shows that alloying GaAs with ≤ 5.1 % Bi dramatically reduces β while leaving α virtually unchanged—enabling a 2 to 100-fold enhancement of the GaAs α/β ratio while extending the wavelength beyond 1.1 µm. Such a dramatic change in only β is unseen in any other dilute alloy and is attributed to the Bi-induced increase of the spin-orbit splitting energy (∆so). Valence band engineering in this way offers an attractive route to enable low noise semiconductor APDs to be developed.

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