In-situ measurements of the irradiation effects in semiconductors under high energy ion irradiation

通过测量辐照下的发光光谱，分析了高能离子在不同半导体中产生的高密度激发效应和局域高温态。用OMA测量了其时间积分发光光谱。用时间相关法测量了其时间分辨光谱。首先，我们通过测量有机-无机层状钙钛矿材料的发光光谱，成功地观察到了沿离子轨迹的暂态局域高温态，这种材料由于自由激子而形成自然的多量子阱结构，并表现出快速的发光。此外，从观测到的局部温度与激发密度之间的关系可以看出，局部熔化是发生的。其次，我们分析了激发子…的空间行为从硫化镉的时间分辨发光光谱中得到更多的载流子。通过分析电子-空穴等离子体产生的快速发光带的光谱形状，我们估算了辐射复合时激发载流子的密度和平均能量。这些结果可以在考虑激发载流子的极性光学散射的扩散模型中得到定量的解释。此外，我们还测量了电子晶格耦合略强于半导体的氧化镁单晶的发光光谱。随着激发密度的增加，自由激子产生的发光带强度逐渐减弱，最终消失。相反，另一个发光带出现在自由激子带的低能侧。类似于传统半导体的情况，我们将自由激子带的消失和新带的出现分别归因于类似于电子空穴等离子体的集体激发态中库仑相互作用的屏蔽和辐射复合。较少

We analyzed the high-density excitation effects and local high temperature state induced by energetic ions in various semiconductors by measuring the luminescence spectra under irradiation. Time-integrated luminescence spectra were measured with an OMA. Time-resolved spectra were measured with a time-correlated. single photon counting system, which determined the arrival time of ions by detecting with multichannel plates the secondary electrons emitted when the ions transmit a carbon foil.At first, we have succeeded in observing the transient local high-temperature state along an ion trajectory by measuring the luminescence spectra of organic-inorganic layered perovskite materials, which is known to form a natural multiple quantum well structure and exhibit fast luminescence due to free excitons. Furthermore, from the relation between the observed local temperature and the excitation density, it was found that local melting occurs.Secondly, we analyzed the spatial behavior of the excit … More ed carriers from the time-resolved luminescence spectra of CdS. By analyzing the spectral shape of a fast aluminescence band due to electron-hole plasma, we estimated the density and the average energy of the excited carriers when radiative recombination occurs. The obtained results can be quantitatively explained within the diffusion model where polar optical scattering of the excited carriers is taken into account.In addition, we measured the luminescence spectra of a single crystal of MgO, in which the electron lattice coupling is slightly stronger than in semiconductors. As the excitation density increased, a luminescence band due to free excitons reduced its intensity, and finally disappeared. In contrast, another luminescence band appeared at the low-energy side of the free exciton band. Similarly to the case of conventional semiconductors, we attributed the disappearance of the free exciton band and the appearance of the new band to the screening of the Coulomb interaction and the radiative recombination in the collective excited states analogous to the electron hole plasma, respectively. Less