Novel III-V heterostructures and designs for high-performance avalanche photodiode devices

雪崩光电二极管（APD）是一种专门的半导体器件，用于检测光，在某些应用中，甚至是单个光子。因此，APD通常用于需要灵敏检测光的各种应用中。它们已成功制造用于不同波段的操作、测距应用和各种光传感解决方案。这些器件的一个共同特征是倍增区：一个电场强度非常高的区域，在该区域中，激发的光电流引起一连串的碰撞电离，在阳极和阴极产生显着放大的信号。APD器件在1.5微米波长范围内有多种应用。InP基外延材料已经被完善以优化使用InGaAs和InP异质结构的APD性能。通过外延掺杂和扩散掺杂相结合的方法，在这些材料中获得了掺杂分布，进一步提高III-V族APD的性能，补充现有的基准产品，对于拓展新的应用具有重要意义.需要改进的具体领域包括暗电流（体电流和表面电流）、雪崩区更陡的I-V曲线（因此APD可以在更远离击穿电压的情况下更安全地工作）、更低的固有噪声等效功率（从而在接收超低光级时获得更好的信噪比（SNR））以及在激光测距仪应用中实现更远的测距。APD需要特殊的设计和工艺控制，因为启动雪崩增益的电场具有非常严格的要求，并且创建III-VAPD所需的各种层的材料和掺杂水平的相互作用是复杂的，具有窄范围的值，可以预期产生良好的性能。该CRD项目将通过设计具有更好优化的AlInAs/InGaAs/InP外延层和掺杂设计的新颖异质结构策略来优化APD器件性能。

An avalanche photodiode (APD) is a specialized semiconductor device used for the detection of light and, incertain applications, even individual photons. The APDs are therefore typically used in various applicationsrequiring sensitive detection of light. They have been successfully manufactured for operation at differentwavelengths, for ranging applications, and various light sensing solutions. A common feature of these devicesis a multiplication region: a region of very high electric field strength in which excited photo-current causes acascade of impact ionizations yielding a significantly amplified signal at the anode and cathode. There areseveral applications for APD devices in the wavelength range of 1.5microns. The InP-based epitaxial materialshave been perfected to optimize the APD performance using InGaAs and InP heterostructures. The dopingprofiles have been obtained by combining epitaxial doping and diffusion doping technique in these materials.To expand into new applications it is important to further improve the performance of such III-V APDs andcomplement the available baseline products. Specific areas for improvement are dark currents (bulk andsurface), steeper I-V curve in the avalanche region so the APD can be operated more safely further from thebreakdown voltage, and lower intrinsic noise equivalent power for better signal-to-noise ratio (SNR) whenreceiving ultra-low light levels and enabling further ranging in laser-range finder applications. APDs requireexceptional design and process controls since the electric fields that initiate avalanche gain have very tightrequirements and the interaction of the materials and doping levels of the various layers needed to create a III-VAPD are complex with a narrow range of values that can be expected to yield good performance. This CRDproject will allow the optimization of the APD device performance by designing novel heterostructurestrategies with better optimized AlInAs/InGaAs/InP epilayers and doping designs.