The development of semiconductors is always accompanied by the progress in controllable doping techniques. Taking AlGaN-based ultraviolet (UV) emitters as an example, despite a peak wall-plug efficiency of 15.3% at the wavelength of 275 nm, there is still a huge gap in comparison with GaN-based visible light-emitting diodes (LEDs), mainly attributed to the inefficient doping of AlGaN with increase of the Al composition. First, p-doping of Al-rich AlGaN is a long-standing challenge and the low hole concentration seriously restricts the carrier injection efficiency. Although p-GaN cladding layers are widely adopted as a compromise, the high injection barrier of holes as well as the inevitable loss of light extraction cannot be neglected. While in terms of n-doping the main issue is the degradation of the electrical property when the Al composition exceeds 80%, resulting in a low electrical efficiency in sub-250 nm UV-LEDs. This review summarizes the recent advances and outlines the major challenges in the efficient doping of Al-rich AlGaN, meanwhile the corresponding approaches pursued to overcome the doping issues are discussed in detail.

空间光学载荷需要在洁净、暗黑、温湿度和压强适宜的实验环境中进行测试，为使模拟实验条件更接近空间环境尤其是光照环境，在千级洁净实验室中搭建了一套适合空间光学载荷成像和杂散光测试的多参量传感系统，可实时监测实验中灰尘粒子数、环境光分布、温湿度和大气压强，开发了基于LabVIEW的控制程序通过串口管理各传感器，对环境条件数据进行采集、存储和综合分析。测试表明：该监测系统能够对弱光环境下的尘埃粒子、大气状态进行实时监测和综合分析，提高了光学载荷自动化测试的监测能力和校准数据的可靠性。

Spin injection and detection in bulk GaN were investigated by performing magnetotransport measurements at low temperatures. A non-local four-terminal lateral spin valve device was fabricated with Co/GaN Schottky contacts. The spin injection efficiency of 21% was achieved at 1.7 K. It was confirmed that the thin Schottky barrier formed between the heavily n-doped GaN and Co was conducive to the direct spin tunneling, by reducing the spin scattering relaxation through the interface states.

在眼科显微手术中，传统的术中成像方式由于缺少深度信息，限制了内部结构和手术器械的可视化。光学相干层析成像技术(OCT)是一种非接触式断层成像技术，由于其能提供深度信息、非侵入、成像快、分辨率高等优点，被广泛应用于眼科手术的术中导航。典型的OCT设备可分为手持OCT和显微镜集成OCT。本文简要介绍了时域OCT和频域OCT的原理和发展，回顾了OCT眼科手术导航设备的发展历程，并对各个类别中有代表性的OCT系统进行了介绍，对其成像原理、性能、优缺点等进行了描述和对比，最后对该技术在眼科手术中的应用做出了总结和展望。