Cao Yuke, Pomeroy James W, Kuball Martin
Opt Lett. 2024 Jul 15;49(14):4034-4037. doi: 10.1364/OL.525927.
Characterizing electric fields in semiconductor devices using electric field-induced second-harmonic generation (EFISHG) has opened new opportunities for an advanced device design. However, this new technique still has challenges due to the interference between background second-harmonic generation (SHG) and EFISHG generated light. We demonstrate that interference effects can effectively be eliminated during EFISHG measurements by focusing the laser from the transparent substrate side of a GaN PN diode, enabling straightforward quantitative electric field analysis, in contrast to PN junction interface side measurements. A model based on wave generation and propagation is proposed and highlights the incoherence between background SHG and EFISHG light. This incoherence may be attributed to the depth of focus of the incident laser and phase mismatch between incident and SHG light.
利用电场诱导二次谐波产生（EFISHG）来表征半导体器件中的电场，为先进器件设计带来了新机遇。然而，由于背景二次谐波产生（SHG）与EFISHG产生的光之间存在干扰，这项新技术仍面临挑战。我们证明，在EFISHG测量过程中，通过从GaN PN二极管的透明衬底一侧聚焦激光，可有效消除干扰效应，与PN结界面侧测量相比，能够实现直接的定量电场分析。提出了一个基于波产生和传播的模型，该模型突出了背景SHG与EFISHG光之间的非相干性。这种非相干性可能归因于入射激光的焦深以及入射光与SHG光之间的相位失配。
