Photonic sensing platform based on photocorrosion of III-V semiconductor microstructures

本项目旨在探索由异质结构、量子阱（QW）或量子点（QD）组成的III-V型半导体微结构的电化学和光学性质，用于检测固定在这些微结构表面附近的带电生物分子。光致发光（PL）效应对半导体表面附近的能带弯曲以及表面状态的密度和性质的改变的敏感性是化学和生物传感中众所周知的效应。我们最近发现，如果在由光激发功率、平均光子通量和半导体周围电解质的蚀刻功率决定的优化条件下诱导半导体异质结构的光腐蚀，可以成为发生在距离半导体表面不到40 nm的距离上的电化学或生化反应的指纹。利用光腐蚀效应监测表面反应为基于pl的表面固定化生物分子检测增加了一个有吸引力的维度。我们已经观察到外延生长的GaAs/AlGaAs异质结堆叠的解离过程，通过使用被这种异质结构埋藏的GaAs层的PL。1纳米薄砷化镓层的原位光腐蚀能力表明，这种方法可以为监测涉及低浓度带电生物分子的反应提供有吸引力的条件。这种“反向分子束外延”的另一个潜在优势涉及半导体光腐蚀暴露表面的原位生物功能化。这可以创造优化的条件，例如，用于高质量自组装单层（SAM）的生长，否则需要应用昂贵的真空或高纯度环境控制设备。十（10）个GaAs/AlGaAs异质结堆叠的光腐蚀实验结果表明，具有更多异质结的器件可以设计用于生物功能化和连续监测发生在其附近的生化反应。基于光腐蚀诊断的创新特性，以及这种方法的潜力，导致了一类新的（生物）传感器和技术，以监测涉及带电分子的表面反应，已经创建了本文档中描述的程序的基础。该计划的核心是开发带电分子在液体环境中与不同半导体微结构表面相互作用的定量（或准定量）图像。这将导致一系列具有异质结构堆栈的设备的构建，QW或QD经过优化，可以快速且以极具吸引力的成本产生敏感的诊断。

This program aims at exploring both electrochemical and optical properties of III-V semiconductor microstructures comprising heterostructures, quantum wells (QW) or quantum dots (QD) for detection of electrically charged biomolecules immobilized in the vicinity of the surface of such microstructures. The sensitivity of the photoluminescence (PL) effect to band bending of a semiconductor near its surface and modification of both density and nature of the surface states is a well known effect investigated for chemical and biological sensing. We have discovered recently that photocorrosion of a semiconductor heterostructure, if induced under optimized conditions determined by light excitation power, average photon fluence and etching power of a semiconductor surrounding electrolyte, could become a fingerprint of the electrochemical or biochemical reactions taking place at distances, typically, less than 40 nm from the semiconductor surface. The employment of the photocorrosion effect for monitoring surface reactions adds an attractive dimension to the PL-based detection of surface-immobilized biomolecules. We have observed a dissociation process of a stack of epitaxially-grown GaAs/AlGaAs heterojunctions, by employing PL of a GaAs layer buried by such heterostructures. The ability to resolve in situ the photocorrosion of a 1 nm thin GaAs layer has suggested that this approach could offer conditions attractive for monitoring the reactions involving low concentrations of electrically charged biomolecules. Another potential advantage of this “reverse molecular beam epitaxy” concerns in situ biofunctionalization of the photocorrosion-revealed surface of a semiconductor. This could create conditions optimized, e.g., for the grow of high-quality self-assembled monolayers (SAM) that otherwise requires the application of expensive vacuum or high-purity environment controlling equipment. The results of the photocorrosion experiment with a stack of ten (10) GaAs/AlGaAs heterojunctions have suggested that devices with even larger number of heterojunctions could be designed for biofunctionalization and sequential monitoring of biochemical reactions taking place in their vicinity. The innovative character of the photocorrosion-based diagnostics, and the potential of this approach to lead to a new class of (bio)sensors and techniques to monitor surface reactions involving electrically charged molecules, have created the base of a program described in this document. At the center of the program is the development of a quantitative (or a quasi-quantitative) picture of charged molecules interacting in a liquid environment with surfaces of different semiconductor microstructures. This will lead to the construction of a family of devices with stacks of heterostructures, QW or QD optimized for yielding a sensitive diagnostics, rapidly and at a highly attractive cost.