SiGe/Si单光子雪崩光电二极管仿真

通过理论模拟CMOS工艺兼容的SiGe/Si 单光子雪崩二极管,研究并讨论了掺杂条件对于电场分布、频宽特性、以及器件量子效率的影响。设计出具有浅结结构、可在盖革模式下工作、低击穿电压(30 V)的1.06 m单光子技术雪崩光电二极管。器件采用分离吸收倍增区结构,其中Si材料作为倍增区、SiGe材料作为吸收区,这充分利用了硅材料较高的载流子离化比差异,降低了器件噪声;在1.06 m波长下,SiGe探测器的量子效率为4.2%,相比于Si探测器的效率提高了4 倍。仿真表明优化掺杂条件可以优化电场分布,从而在APD击穿电压处获得更好的带宽特性。     

Optical characteristics of a superlattice avalanche photodiode

Avalanche photodiodes using III–V materials are suitable for use in long distance fiber optic communication systems due to their faster speed of response and high gain. The superlattice APD is expected to be far more attractive than the conventional APD for their better noise performance. Theoretical studies have been carried out on the photoresponse characteristics of an Al_xGa_1−xAs/GaAs superlattice p⁺−i−n⁺ structure. It is observed that for a particular d.c. multiplication factor the normalised gain of the device remains constant with frequency and falls steadily after a certain frequency. The band width of the response curve increases with decrease in d.c. multiplication factor. Furthermore, the output current of the superlattice structure increases with the increase in optical power. The device also shows a good percentage of quantum efficiency.     

Equivalent-circuit parameters of a silicon avalanche photodiode

The dependence of the relative phase shift in a silicon avalanche photodiode on the multiplication is used for the determination of the intrinsic response time in the avalanche region. The value of the intrinsic response time of a silicon avalanche photodiode was found to be 0.85 ps. The procedure used to estimate the equivalent-circuit parameters of the detector is also described.     

An optimized avalanche photodiode

The feasibility of a fast, high-gain photodetector based on the phenomenon of avalanche multiplication in semiconductors has been investigated. Based on the process of carrier multiplication in a high electric field, criteria for the design of an optimized avalanche photodiode and for the choice of the best semiconductor material are developed. The device theory of an optimized, realizable avalanche photodiode is presented. A practical silicon device optimized for the detection of light with a wavelength of 9000Å is suggested and design parameters are presented. Details of the fabrication process are given and the performance of experimental devices is compared to the device theory presented. The results of the study indicate that it is possible to achieve a silicon photomultiplier with a quantum efficiency-bandwidth product of the order of 100 GHz for the detection of light up to a wavelength of over 9000Å.     

一种高速雪崩光电探测器

High-speed avalanche photodiodes are widely used in optical communication systems. Nowadays, separate absorption charge and multiplication structure is widely adopted. In this article, a structure with higher speed than separate absorption charge and multiplication structure is reported. Besides the traditional absorption layer, charge layer and multiplication layer, this structure introduces an additional charge layer and transit layer and thus can be referred to as separate absorption, charge, multiplication, charge and transit structure. The introduction of the new charge layer and transit layer brings additional freedom in device structure design. The benefit of this structure is that the carrier transit time and device capacitance can be reduced independently, thus the 3 dB bandwidth could be improved by more than 50% in contrast to the separate absorption charge and multiplication structure with the same size.     

碲镉汞雪崩焦平面器件

碲镉汞雪崩光电二极管以其高增益、高灵敏度和高速探测的优点成为第3代红外光电探测器的重要发展方向之一.制备了截止波长3.56μm的雪崩光电二极管焦平面器件,面阵规模为16×16.焦平面器件在0～6V偏压下有效像元率大于90%,非均匀性小于20%.6 V偏压下NEPh约为60,过剩噪声因子为1.2.     

基于目标/系统特征设计雪崩光电二极管增益

以即时全球打击(prompt global strike,PGS)武器的早期预警为应用背景,介绍了理想条件下从PGS投射到探测器上光子数的估算方法。给出了基于探测器量子效率的光生电荷数的计算方法。讨论了PGS辐射特征和运动特征、光生电荷数以及可检测电流阈值对于APD增益设计的影响。     

碲镉汞APD平面型PIN结构仿真设计研究

碲镉汞(HgCdTe)线性雪崩焦平面因其相对低的过剩噪声、较小的工作电压、线性可调等优点,得到了广泛关注。基于电子雪崩中波HgCdTe PIN二极管结构,开展暗电流模型和Okuto-Crowell增益模型仿真。通过改变器件材料结构参数模拟不同电压下的暗电流和增益特性。计算讨论了不同I区(本征区)厚度和载流子浓度对器件暗电流和增益的影响。结果表明结区峰值场强的变化会导致直接隧穿(BBT)电流产生率数量级上的剧烈变化;增加I区厚度和降低I区掺杂浓度可有效抑制BBT电流;增益随场强的变化趋势与BBT电流随场强的变化趋势一致;因此抑制BBT电流的措施会造成增益性能的下降,需要优化参数以获得最佳性能。综合考虑暗电流和增益性能,I区的厚度应不小于3μm,I区浓度需控制在5×10¹⁴cm^-3以下。单元中波APD的增益实验结果与仿真数据较好地吻合,表明了理论模型的正确性。     

Effect of avalanche build-up time on avalanche photodiode sensitivity

A calculation method for the receiver sensitivity of an avalanche photodiode is considered, taking into account avalanche build-up time and carrier transit time, in addition to the CR time constant. Actual receiver performance is estimated in a high data rate region of up to 10 Gbits/s for germanium avalanche photodiodes, applying the measured avalanche build-up time.     

Low-voltage high-gain resonant-cavity avalanche photodiode

For p-i-n photodiodes and avalanche photodiodes (APDs) in the low-gain regime, there is a performance tradeoff between the transit-time contribution to the bandwidth and the quantum efficiency. A new photodetector structure is demonstrated that alleviates limitations imposed by this tradeoff. This structure utilizes a thin ( approximately=900 AA) depleted absorbing layer to reduce the transit time and achieve avalanche gain at low bias voltage (V/sub b/ approximately=9 V). The external quantum efficiency has been enhanced ( eta /sub e/>49%) by incorporating the structure into a resonant cavity.<>     

High gain-bandwidth product Ge/Si tunneling avalanche photodiode with high-frequency tunneling effect

This study presents a theoretical investigation of a novel Ge/Si tunneling avalanche photodiode (TAPD) with an ultra-thin barrier layer between the absorption and p⁺ contact layer. A high-frequency tunneling effect is introduced into the structure of the barrier layer to increase the high-frequency response when frequency is larger than 0.1 GHz, and the -3 dB bandwidth of the device increases evidently. The results demonstrate that the avalanche gain and -3 dB bandwidth of the TAPD can be influenced by the thickness and bandgap of the barrier layer. When the barrier thickness is 2 nm and the bandgap is 4.5 eV, the avalanche gain loss is negligible and the gain-bandwidth product of the TAPD is 286 GHz, which is 18% higher than that of an avalanche photodiode without a barrier layer. The total noise in the TAPD was an order of magnitude smaller than that in APD without barrier layer.     

Multigigabit-per-second avalanche photodiode lightwave receivers

High-speed avalanche photodiodes and high-sensitivity receivers are vital components for future multigigabit-per-second lightwave transmission systems. We review theoretical and experimental performance of high-speed III-V avalanche photodiodes, and also that of multigigabit-per-second lightwave receivers using FET and bi-polar amplifiers. Particular attention is given to APD gain-bandwidth product, and to its effect on high-speed receiver sensitivity. Comparisons between measured receiver sensitivities and calculated performance are presented for bit rates up to 8 Gbit/s.     

The HgCdTe electron avalanche photodiode

Electron injection avalanche photodiodes in short-wave infrared (SWIR) to long-wave infrared (LWIR) HgCdTe show gain and excess noise properties indicative of a single ionizing carrier gain process. The result is an electron avalanche photodiode (EAPD) with “ideal” APD characteristics including near noiseless gain. This paper reports results obtained on long-, mid-, and short-wave cutoff infrared Hg_1−xCd_xTe EAPDs (10 μm, 5 μm, and 2.2 μm) that use a cylindrical “p-around-n” front side illuminated n+/n-/p geometry that favors electron injection into the gain region. These devices are characterized by a uniform, exponential, gain voltage characteristic that is consistent with a hole-to-electron ionization coefficient ratio, k=α_h/α_e, of zero. Gains of greater than 1,000 have been measured in MWIR EAPDS without any sign of avalanche breakdown. Excess noise measurements on midwave infrared (MWIR) and SWIR EAPDs show a gain independent excess noise factor at high gains that has a limiting value less than 2. At 77 K, 4.3-μm cutoff devices show excess noise factors of close to unity out to gains of 1,000. A noise equivalent input of 7.5 photons at a 10-ns pulsed signal gain of 964 measured on an MWIR APD at 77 K provides an indication of the capability of this new device. The excess noise factor at room temperature on SWIR EAPDs, while still consistent with the k=0 operation, approaches a gain independent limiting value of just under 2 because of electron-phonon interactions expected at room temperature. The k=0 operation is explained by the band structure of the HgCdTe. Monte Carlo modeling based on the band structure and scattering models for HgCdTe predict the measured gain and excess noise behavior.     

Optimum design of δ-doped InGaAs avalanche photodiode byusing quasi-ionization rates

An avalanche photodiode (APD) designed by using quasi-ionization rates in InP and InGaAs is described. The structure has a δ-doped layer in an InP window layer. The heterointerface electric field is investigated and determined to prevent the tunneling current and carrier multiplication in InGaAs. The gain bandwidth (GB) product of the δ-doped APD is analyzed by R.B. Emmons's (1967) p-i-n electric field method. The highest GB product is 160 GHz     

碲镉汞雪崩光电二极管发展现状

碲镉汞雪崩光电二极管探测器具有高增益、高带宽和低噪声因数的显著特点,具有下一代焦平面探测器阵列的多功能、主动/被动探测、双波段和高灵敏度等理想特性,在低光通量探测、超光谱、二维/三维成像方面显示出强大的应用潜力。本文简要介绍了碲镉汞雪崩光电二极管主要器件结构、特点及应用现状。     

Transfer matrix modeling of avalanche photodiode

In this article,we calculated and modeled the gain of In0.53Ga0.47As/InP avalanche photodiode (APD) based on a device mechanism and cartier rate equations using transfer matrix method (TMM).In fact,a d...     

A model of the avalanche photodiode

A general model for the avalanche photodiode is presented. It is shown that the diode consists of four regions: 1) guard ring, 2) uniform avalanche region, 3) high-field absorption region and 4) zero-field absorption region. Expressions are given for the ac quantum efficiency, the dc quantum efficiency, and the transit time cutoff frequency. Material requirements are discussed. Based on an entire detector system, an expression is derived for the signal-to-noise ratio. An example is given with the result that a noise-equivalent power (NEP) of 10^-12W/Hz^1/2is obtained with an optimum avalanche gain of approximately 23.     

An avalanche photodiode with metal-insulator-semiconductor properties

A new design of the avalanche photodetector combining the avalanche photodiode and MIS structure properties was tested. The noise and high-frequency properties of the device were studied. The device exhibited a noise factor of less than 10 at a high multiplication factor (M>1000) even with hole injection. This is indicative of a drastic change in the effective ratio of the coefficients of impact ionization by electrons and holes in favor of the latter. Measurements of the photosensitivity distribution over a photodetector area for M=8000 showed a high uniformity.     

InGaAsP/InAlAs superlattice avalanche photodiode

The fabrication of an InGaAsP-InAlAs superlattice avalanche photodiode using a gas source molecular beam epitaxy is discussed. A quaternal alloy of InGaAsP was used for the well layers in order to suppress the dark current due to the tunneling effect. With this structure, the valance band discontinuity almost vanishes and a gain bandwidth of 110 GHz was obtained