Dislocations provide fast diffusion pathways for atoms in semiconductors which can alter compositional profiles of finely tuned heterostructures. We show in model lattice-mismatched IV-VI semiconductor heterostructures of SnSe/PbSe on GaAs substrates that threading dislocations are highly enriched with group IV species of the neighboring layer, with artifacts that reflect the dynamic nature of dislocations when growing dissimilar materials as well as altered bonding properties at the dislocation core. Using atom probe tomography, we characterize one-dimensional nanometer-wide Sn-enriched filaments, which extend downward from SnSe through threading dislocations in the PbSe layer and infiltrate the remote PbSe/GaAs interface through the misfit dislocation network in the short time of growth. Local Sn compositions of only 6%–8% around the dislocations are significantly lower than the 30% Sn expected in bulk PbSe. We estimate the diffusivity of Sn atoms along threading dislocations to be ${10}^{–14}\mathrm{c}{\mathrm{m}}^2{\mathrm{s}}^{–1}$ at 300 °C, approximately three orders of magnitude larger than the lattice diffusivity. In contrast, Pb atoms from PbSe either do not diffuse upward into the orthorhombic SnSe layer or do so only a short distance as one-dimensional filaments before abruptly stopping, likely due to the nature of SnSe on PbSe epitaxy involving lattice mismatch. Beyond compositional anomalies, we detect elevated multiple-atom evaporation events that are spatially correlated to the dislocation, over and above an already high baseline in the matrix. In mixed-bonded IV-VI materials, where previous work has linked such events to the nature of bonding, we find that dislocations show up as distinct from the matrix.

中文翻译：

---

SnSe/PbSe 异质结构中的管道扩散富集位错和界面

位错为半导体中的原子提供了快速扩散途径，可以改变微调异质结构的成分分布。我们在 GaAs 衬底上的 SnSe/PbSe 的晶格失配 IV-VI 半导体异质结构模型中显示，穿透位错高度富含相邻层的 IV 族物质，具有反映异种材料生长时位错动态性质的伪影以及位错核心处的键合特性改变。使用原子探针断层扫描，我们表征了一维纳米宽的富锡细丝，这些细丝从 SnSe 向下延伸通过 PbSe 层中的穿透位错，并在短时间内通过错配位错网络渗透到远程 PbSe/GaAs 界面。位错周围仅 6%–8% 的局部 Sn 成分显着低于块状 PbSe 中预期的 30% Sn。我们估计 Sn 原子沿穿透位错的扩散系数为${10}^{——14}\mathrm{C}{\mathrm{米}}^2{\mathrm{秒}}^{——1}$在 300 °C 时，大约比晶格扩散率大三个数量级。相比之下，来自 PbSe 的 Pb 原子要么不会向上扩散到正交 SnSe 层，要么在突然停止之前仅作为一维细丝扩散一小段距离，这可能是由于 PbSe 外延涉及晶格失配的 SnSe 的性质。除了成分异常之外，我们还检测到与位错在空间上相关的多原子蒸发事件升高，超过了基质中已经很高的基线。在混合键合 IV-VI 材料中，之前的工作已将此类事件与键合的性质联系起来，我们发现位错与基体不同。