【作者】 周鹏；

【导师】 李淳飞； 廖常俊；

【作者基本信息】 哈尔滨工业大学 ， 光学， 2010， 博士

【摘要】 单光子探测是一种重要的技术,被广泛应用在量子保密通信、量子计算和测量灵敏度需要达到单光子水平的其他领域。对于1310nm和1550nm的通信波段,具有吸收、渐变、电荷、倍增分区结构（SAGCM）的In0.53Ga0.47As/InP雪崩光电二极管（APD）被广泛地研究,并认为是最具实用性的单光子探测器。因为APD工作在反偏压高于雪崩击穿电压条件下,即处于所谓的盖革模式下,所以它也被叫作盖革模式雪崩光电二极管或者单光子雪崩二极管（SPAD）。本论文通过理论和实验研究了SAGCM In0.53Ga0.47As/InP SPAD的雪崩击穿特性,观察并解释了相对电流增益饱和的现象。据此提出了一种能够简单准确地测量SPAD的贯穿电压和雪崩击穿电压的方法。该方法不依赖于温度,具有很好的实用性。采用了历史相关的碰撞电离模型,通过数值分析的方法,研究了具有SAGCM结构的In0.53Ga0.47As/InP SPAD击穿电压的影响因素。计算结果表明击穿电压会随着温度的升高,电荷层电荷密度的增大而升高。同时存在某一特征倍增区厚度,当SPAD倍增区厚度小于这一特征值时,雪崩击穿电压会随倍增区厚度增大而降低;而当倍增区厚度大于这一特征值时,击穿电压会随之缓慢升高。提高单光子探测性能有两种有效的途径,首先是设计单光子探测专用的SPAD,然后是改进器件的驱动和控制技术。本文给出了一种In0.53Ga0.47As/InP SPAD的结构和参数设计,通过控制倍增区、吸收区及电荷层的厚度和掺杂浓度,使其更适用于单光子探测。为了尽可能地减少暗计数,提高单光子量子效率,优化器件的结构和驱动电路,有必要弄清产生暗计数的物理机制,以及单光子量子效率和暗计数概率对器件结构和工作条件的依赖关系。本文提出了一个比较严格的模型来计算SPAD的单光子量子效率和暗计数概率,在此模型中考虑了电荷层和吸收区的碰撞电离对倍增区雪崩击穿的贡献,假设雪崩击穿只能发生在倍增区。计算雪崩击穿概率与电场的关系时,采用了历史相关的碰撞电离模型。在较宽的温度范围内,计算了不同结构、不同偏置电压下的SPAD的单光子量子效率和暗计数概率。结果表明,如果忽略了电荷层和吸收区的碰撞电离,将会导致对暗计数的低估,低估率随着温度的升高而升高。增大倍增区会提高SPAD的峰值单光子量子效率,但是如果倍增区厚度超过1μm,峰值单光子量子效率随着Wm的升高会变得非常缓慢,并最终达到饱和而接近器件的内量子效率。决定SPAD暗计数的物理机制取决于器件的结构和工作条件。当SPAD倍增区较薄时,暗计数的最主要来源是倍增区的隧穿;当SPAD倍增区较厚时,暗计数的决定性机制为吸收区的产生-复合效应。对于倍增区为1μm左右的SPAD,当温度较低时,倍增区的隧穿是暗计数的最主要来源,随着温度的升高,吸收区的产生-复合作用变得重要起来,当温度达到某一特定值时,吸收区的产生-复合成为暗计数的最主要来源。改进了SPAD的驱动和控制技术,提出了积分门控模式单光子探测器方案,并给出了实验验证。与通常门控模式不同,在这个方案中,通过检测雪崩脉冲的电荷量,使电尖峰问题得到了很好的解决,进而有效地提高了单光子探测器的性能。对于1550nm波长,单光子量子效率达到了29.9%,同时每门暗计数降到了5.57×10^-6,即达到1.11×10^-7/ns。更多还原

【Abstract】 Single photon detectors are increasingly needed in the emerging fields of quantum computation and quantum cryptography as well as in some more traditional fields that requiring single photon sensitivity. As in the telecom wavelengths of 1310 and 1550nm, a separate absorption, grading, charge and multiplication (SAGCM) In0.53Ga0.47As/InP avalanche photodiode (APD) that reverse biased beyond breakdown voltage (VB) and operated in so-called Geiger mode is regarded as one of the most practical single photon detectors. These APDs are also known as Geiger mode avalanche photodiodes or single photon avalanche diodes (SPADs).In this thesis, characteristics of the avalanche breakdown in SAGCM In0.53Ga0.47As/InP SPADs are analyzed numerically and experimentally. In the experiment, saturation of the relative current gain is observed and interpreted. According to this, the punch-through voltage and breakdown voltage of single photon avalanche diodes can be measured in a simple and accurate way. The analysis method is temperature independent and more practical.The structure and operation dependence of breakdown voltage is also calculated. The results indicate that the breakdown voltage increases with the temperature and charge density in the charge layer. And there is a critical value of the multiplication layer width Wm0. When the multiplicition layer width (Wm) is smaller than Wm0, VB decreases with Wm. While VB increases slowly with when Wm is above Wm0. An improved structure of In0.53Ga0.47As/InP SPAD is proposed in which the width and doping concentration of the multiplication, absorption and charge layer is carefully designed specially for single photon detection.In order to optimize the structure design and operation of SPADs, it is necessary to clarify the mechanisms that give rise to dark counts, as well as the dependence of SPQE and Pd on the structure, voltage and temperature. In the thesis, a more rigorous model is developed to determine the SPQE and Pb, in which impact ionization in charge and absorption layers have been taken into account to have contribution to the avalanche breakdown which can take place only in the multiplication region. In the temperature range of 200-300K, dark count rate of SPADs with 0.2-3μm multiplication layer was calculated. Results show that, ignoring the impact ionization of charge and absorption layer will cause an underestimate of dark counts. The ratio of underestimate increases with temperature. The results also show that the primary mechanism of dark counts depends on both device structure and operating conditions. The thickness of charge layer greatly affects the dark counts and peak SPQE. The peak SPQE rises with the increase of multiplication layer width. But when Wm > 1μm, the peak SPQE increases slowly and it finally saturates at the quantum efficiency of the SPAD. The primary origin of dark counts depends on both device structure and operating conditions. For SPADs with thinner multiplication layer, band to band tunneling in multiplication layer is the dominative mechanism of dark counts, while for thicker SPADs, generation-recombination in the absorber dominates the dark counts. Dark counts from generation-recombination increase importance with temperature. As for a SPAD with multiplication layer arround 1μm, there is a critical temperature, when the operating temperature below the critical temperature, tunneling is the primary origin of dark counts, while when the operating temperature exceed the critical temperature, generation-recombination in the absorption layer begins to dominate.An integral gated mode single photon detector is demonstrated at telecom wavelengths. The charge number of an avalanche pulse rather than the peak current is monitored for single photon detection. The transient spikes in conventional gate mode operation are cancelled completely by integrating, which effectively improves the performance of the single photon detector. This method may achieve a detection efficiency of 29.9% at the dark count probability per gate equals to 5.57×10-6/gate (1.11×10-7/ns) at 1550nm.更多还原