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We report a, to the best of our knowledge, new device fabrication process for 128-pixel linear arrays of InAs planar avalanche photodiodes, utilizing selective area implantation of Beryllium ions into epitaxially-grown InAs wafers. The pixels exhibited uniform avalanche gain and responsivity. Room temperature responsivity values at 1550 and 2004 nm wavelengths are 0.49 ± 0.017 and 0.89 ± 0.024 A/W, respectively. Reverse dark current-voltage and avalanche gain measurements were carried out at different temperatures (from room temperature to 150 K). At 200 K at -15 V reverse bias, the pixels exhibited an avalanche gain of 22.5 ± 1.18 and dark current density of 0.68 ± 0.48 A/cm 2 .

Al 0.85 Ga 0.15 As 0.56 Sb 0.44 is a promising avalanche material for near infrared avalanche photodiodes (APDs) because they exhibit very low excess noise factors. However electric field dependence of ionization coefficients in this material have not been reported. We report a Simple Monte Carlo model for Al 0.85 Ga 0.15 As 0.56 Sb 0.44 , which was validated using reported experimental results of capacitance-voltage, avalanche multiplication and excess noise factors from five APDs. The model was used to produce effective ionization coefficients and threshold energies between 400-1200 kV.cm -1 at room temperature, which are suitable for use with less complex APD simulation models.

An avalanche photodiode with a ratio of hole-to-electron ionization coefficients, k = 0, is known to produce negligible excess noise irrespective of the avalanche gain. The low noise amplification process can be utilized to detect very low light levels. In this work, we demonstrated InAs avalanche photodiodes with high external quantum efficiency of 60% (achieved without antireflection coating) at the peak wavelength of 3.48 µm. At 77 K, our InAs avalanche photodiodes show low dark current (limited by 300 K blackbody background radiation), high avalanche gain and negligible excess noise, as InAs exhibits k = 0. They were therefore able to detect very low levels of light, at 15-31 photons per 50 µs laser pulse at 1550 nm wavelength. These correspond to the lowest detected average power by InAs avalanche photodiodes, ranging from 19 to 40 fW. The measurement system's noise floor was dominated by the pre-amplifier. Our results suggest that, with a lower system noise, InAs avalanche photodiodes have high potential for optical detection of single or few-photon signal levels at wavelengths of 1550 nm or longer.

Avalanche photodiodes (APDs) with thin avalanche regions have shown low excess noise characteristics and high gain-bandwidth products, so they are suited for long-haul optical communications. In this work, we investigated how carrier injection profile affects the avalanche gain and excess noise factors of Al 0.85 Ga 0.15 As 0.56 Sb 0.44 (lattice-matched to InP substrates) p-i-n and n-i-p diodes with total depletion widths of 145-240 nm. Different carrier injection profiles were achieved by using light with wavelengths of 420, 543 and 633nm. For p-i-n diodes, shorter wavelength light produces higher avalanche gains for a given reverse bias and lower excess noise factors at a given gain, compared to longer wavelength light. Thus, using 420 nm light on the p-i-n diodes, corresponding to pure electron injection conditions, gave the highest gain and lowest excess noise. In n-i-p diodes, pure hole injection yields significantly lower gain and higher excess noise, compared to mixed carrier injection. These show that the electron ionization coefficient, α, is higher than the hole ionization coefficient, β. Using pure electron injection, excess noise factor characteristics with effective ionization ratios, keff, of 0.08-0.1 were obtained. This is significantly lower than those of InP and In 0.52 Al 0.48 As, the commonly used avalanche materials combined with In 0.53 Ga 0.47 As absorber. The data reported in this paper is available from the ORDA digital repository (DOI: 10.15131/shef., Data: 5787318).

With increasing interest over the past decade in space-related remote sensing and communications using near-infrared (NIR) wavelengths, there is a need for radiation studies on NIR avalanche photodiodes (APDs), due to the high radiation environment in space. In this work, we present an experimental study of proton radiation effects on performance parameters of InAs APDs, whose sensitivity extends from visible light to ~3.5 μm. Three irradiation energies (10.0, 31.4, and 58.8 MeV) and four fluences (10 9 to 10 11 p/cm 2 ) were used. At the harshest irradiation condition (10.0 MeV energy and 10 11 p/cm 2 fluence) the APDs' avalanche gain and leakage current showed a measurable degradation. However, the responsivity of the APDs was unaffected under all conditions tested. The data reported in this article are available from the figshare digital repository (DOI: https://dx.doi.org/10.15131/shef., Data: 4560562).

Increasing reliance on the Internet places greater and greater demands for high-speed optical communication systems. Increasing their data transfer rate allows more data to be transferred over existing links. With optical receivers being essential to all optical links, bandwidth performance of key components in receivers, such as avalanche photodiodes (APDs), must be improved. The APDs rely on In 0.53 Ga 0.47 As (grown lattice-matched to InP substrates) to efficiently absorb and detect the optical signals with 1310 or 1550 nm wavelength, the optimal wavelengths of operation for these optical links. Thus developing InP-compatible APDs with high gain-bandwidth product (GBP) is important to the overall effort of increasing optical links' data transfer rate. Here we demonstrate a novel InGaAs/AlGaAsSb APD, grown on an InP substrate, with a GBP of 424 GHz, the highest value reported for InP-compatible APDs, which is clearly applicable to future optical communication systems at or above 10 Gb/s. The data reported in this article are available from the figshare digital repository (https://dx.doi.org/10.15131/shef., Data: 3827460.v1).

An InGaAs/InAlAs Single Photon Avalanche Diode was fabricated and characterized. Leakage current, dark count and photon count measurements were carried out on the devices from 260 to 290 K. Due to better temperature stability of avalanche breakdown in InAlAs, the device breakdown voltage varied by < 0.2 V over the 30 K temperature range studied, which corresponds to a temperature coefficient of breakdown voltage less than 7 mV/K. The single photon detection efficiency achieved in gated mode was 21 and 10% at 260 and 290 K, respectively. However the dark count rates were high due to excessive band-to-band tunneling current in the InAlAs avalanche region.

An Analytical Band Monte Carlo model was used to investigate the temperature dependence of impact ionization in InAs. The model produced an excellent agreement with experimental data for both avalanche gain and excess noise factors at all temperatures modeled. The gain exhibits a positive temperature dependence whilst the excess noise shows a very weak negative dependence. These dependencies were investigated by tracking the location of electrons initiating the ionization events, the distribution of ionization energy and the effect of threshold energy. We concluded that at low electric fields, the positive temperature dependence of avalanche gain can be explained by the negative temperature dependence of the ionization threshold energy. At low temperature most electrons initiating ionization events occupy L valleys due to the increased ionization threshold. As the scattering rates in L valleys are higher than those in Γ valley, a broader distribution of ionization energy was produced leading to a higher fluctuation in the ionization chain and hence the marginally higher excess noise at low temperature.

The optical and electrical properties of InAs quantum dots epitaxially grown on a silicon substrate have been investigated to evaluate their potential as both photodiodes and avalanche photodiodes (APDs) operating at a wavelength of 1300 nm. A peak responsivity of 5 mA/W was observed at 1280 nm, with an absorption tail extending beyond 1300 nm, while the dark currents were two orders of magnitude lower than those reported for Ge on Si photodiodes. The diodes exhibited avalanche breakdown at 22 V reverse bias which is probably dominated by impact ionisation occurring in the GaAs and AlGaAs barrier layers. A red shift in the absorption peak of 61.2 meV was measured when the reverse bias was increased from 0 to 22 V, which we attributed to the quantum confined stark effect. This shift also leads to an increase in the responsivity at a fixed wavelength as the bias is increased, yielding a maximum increase in responsivity by a factor of 140 at the wavelength of 1365 nm, illustrating the potential for such a structure to be used as an optical modulator.