Sawicka Marta, Fiuczek Natalia, Turski Henryk, Muziol Grzegorz, Siekacz Marcin, Nowakowski-Szkudlarek Krzesimir, Feduniewicz-Żmuda Anna, Wolny Paweł, Skierbiszewski Czesław
Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland.
Nanoscale. 2020 Mar 12;12(10):6137-6143. doi: 10.1039/c9nr10968d.
Typical methods of doping quantification are based on spectroscopy or conductivity measurements. The spatial dopant distribution assessment with nanometer-scale precision is limited usually to one or two dimensions. Here we demonstrate an approach to detect three-dimensional dopant homogeneity in GaN:Si layers using electrochemical etching (ECE). GaN:Si layers are grown by plasma-assisted molecular beam epitaxy. Dopant incorporation is uniform when the growth front morphology is atomically flat. Non-uniform Si incorporation into GaN is observed when step-bunches are present on the surface during epitaxy. In this study we show that local Si concentration in the area of step-bunch is about three times higher than in the area between step-bunches. ECE spatial resolution in our experiment is estimated to be about 50 nm. This makes ECE a simple and quantitative probing tool for local three-dimensional conductivity homogeneity assessment. Our study proves that ECE could be important both for fundamental studies of crystal growth physics and impurity incorporation and for ion-implanted structures and post-processing device control.
典型的掺杂定量方法基于光谱学或电导率测量。通常，具有纳米级精度的空间掺杂剂分布评估仅限于一到两个维度。在此，我们展示了一种使用电化学蚀刻（ECE）检测GaN:Si层中三维掺杂均匀性的方法。GaN:Si层通过等离子体辅助分子束外延生长。当生长前沿形态为原子级平整时，掺杂剂掺入是均匀的。在外延过程中，当表面存在台阶束时，会观察到Si不均匀掺入GaN的情况。在本研究中，我们表明台阶束区域的局部Si浓度比台阶束之间的区域高约三倍。我们实验中的ECE空间分辨率估计约为（50纳米）。这使得ECE成为用于局部三维电导率均匀性评估的简单且定量的探测工具。我们的研究证明，ECE对于晶体生长物理学和杂质掺入的基础研究以及离子注入结构和后处理器件控制都可能很重要。
