高压下单根GaAs纳米线的受激辐射特性研究

The near-infrared semiconductor nanowire lasers (SNLs) have attracted extensive attention for the potential applications in telecommunications and spectral analysis. GaAs nanowires have excellent infrared optical properties and have been successfully demonstrated as single near-infrared SNLs. The high density surface states of GaAs become the barrier to the temperature operation of SNLs while the small size of nanowires makes the wave-length modulation quite difficult. Pressure can be used in the wavelength modulation of SNLs because it can directly change the band gap of semiconductor materials. Pressure can also enhance the interactions between the medium and defects on the surface of nanostructure which realize effective passivation on surface state. ..In this project, we propose to use the high pressure diamond anvil cell (DAC) technique which can applied hydrostatic pressure environment and various in-suit optical characterization technique to study systematically the optical properties of GaAs nanowires: 1) we will investigate pressure modulation on the band gap and interband optical transition of GaAs nanowire and try to build physical mode for modulation mechanism; 2) we will measure the minority carrier lifetime in GaAs nanowires passivated with transmission medium under high pressure and calculate the quantum efficiency of radioactive recombination for getting the best passivation conditions; 3) we will optical pumping single GaAs nanowire with femtosecond laser to observe the process from spontaneous emitting to stimulated emitting and study relationship between lowest threshold and environment conditions (temperature, pressure ). The realization of this project can promote the SNLs research for low cost, room temperature, and functional applications. The pressure modulation mechanism on optical (electrical) properties of semiconductor naowires can open a new route for the functionalization of other nano devices.

近红外半导体纳米线激光器（SNLs）在光通信及光谱检测分析方面具有广泛的应用前景，因此备受关注。GaAs材料纳米线具有优异红外光学性质且已经成功实现单根SNLs近红外激光发射。GaAs材料的高密度表面态及纳米结构的小尺寸严重阻碍了近红外SNLs 的室温应用及波长调谐。压力能够直接影响半导体材料的带隙，可以作为SNLs波长的原位调谐手段。压力同样能够促进介质与纳米结构表面缺陷之间的相互作用，实现对于表面态的有效钝化。因此本项目拟采用高压金刚石对顶砧技术及高压光谱技术系统研究GaAs纳米线能带结构及带间跃迁模式的压力调控机制、介质在压力环境下对于GaAs纳米线表面能态的钝化机制及高压下纳米线的受激辐射能量阈值的温度-压力效应。该项目将助于近红外SNLs的低成本、室温化及功能化应用。项目所呈现的纳米线光学性能的压力调控机制研究也将为其他纳米光电器件的功能调控提供新的研究思路。

本项目中，我们主要面向近红外半导体纳米线激光器的室温激光发射和原位波长调谐等问题开展了高压下GaAs纳米线受激辐射特性及其调控机制研究，研究内容主要围绕下面 3个方面进行：.1）GaAs纳米线的结构相变、带隙的压力调控及压制带间跃迁模式转变.研究了高压下GaAs纳米线的晶格常数变化及带隙变化，发现了压力为20.0GPa时，GaAs纳米线的闪锌矿到正交相的相变及压力诱导金属化现象，得到压力导致的纳米线体积压缩率及相应带隙变化规律，建立压力-带隙宽度的关联模型。明确了压力导致的直接跃迁--间接跃迁的转变过程及相应发光效率的变化趋势。.2）高压下传压介质对GaAs纳米线表面的钝化作用.研究高压环境下纳米线样品沉浸到传压介质中所引起的发光特性变化，结合理论计算探索传压介质的分子与纳米线表面的电荷转移效应机制。同时通过对于所施加压力的调谐，研究压不同传压介质在纳米线表面所产生的钝化作用差异。.3）高压下GaAs纳米线的受激辐射研究.在可变功率泵浦下，研究GaAs纳米线自发辐射-受激辐射转变过程。优化实验条件，实现GaAs纳米线的室温受激辐射。.项目的研究成果助于近红外半导体纳米线的低成本、室温化及功能化应用。项目所所呈现的纳米线光（电）性能的压力调控机制研究也将为其他纳米光电器件的功能调控提供新的研究思路。