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We characterized the electric field distribution of GaN-on-GaN p–n diodes with partially compensated ion-implanted edge termination (ET) using an electric field induced second harmonic generation technique (EFISHG). The distributed electric field from the anode to the outer edge of the ET demonstrates the effectiveness of the ET structure. However, EFISHG also shows that its effectiveness is strongly dependent on the acceptor charge distribution in the ET's partially compensated layer (PC). A generally lower amount of acceptor charge can be inferred from the measured electric field distribution resulting from excessive ion implantation energy or dose during ET fabrication and causing lower than optimal breakdown voltage. Localized field crowding can be observed when the remaining acceptors uncompensated by the implant in the PC layer are nonuniformly distributed around the periphery of the devices. Important information can be obtained from these direct electric field measurements and used for optimizing the device design and fabrication process. [ABSTRACT FROM AUTHOR]

Electric field distribution is critically important for quantitative insights into the physics of nonequilibrium plasma like corona. To analyze the electric field as well as the ion flow (space charge) distribution under DC corona discharges, the ion flow model has been widely adopted; Kaptzov's assumption, which states that the steady state electric field at the conductor surface remains at the corona onset value, serves as a boundary condition. In this Letter, we investigate the electric field distribution under DC corona discharges between coaxial cylindrical electrodes in ambient air by electric field induced second harmonic generation with nanosecond pulse laser beams. The electric field distribution (with or without the corona discharge) is obtained. By comparing the measurements with the results predicted by the ion flow model for the negative corona discharge, it is found that the electric field at the conductor surface is proportional to the current density of the corona discharge with a negative constant of proportionality. Therefore, for negative corona discharges, Kaptzov's assumption is valid only when the discharge current approaches zero or is small. [ABSTRACT FROM AUTHOR]

Comment on "Electric field measurements under DC corona discharges in ambient air by electric field induced second harmonic generation" [Appl. Phys. Equation (1) is an approximate relation obtained from the ion transport equation coupled with the Poisson equation, and in order to analyze its validity, one should resort to a more accurate theoretical model, comprising these and other relevant equations. It follows that Eq. (1) with the negative ion mobility does not describe correctly the electric field distribution in the region I r i >= 0.2 cm. The latter is indeed the case, as shown in Fig. [Extracted from the article]

Response to "Comment on 'Electric field measurements under DC corona discharges in ambient air by electric field induced second harmonic generation'" [Appl. Phys. As stated in Ref. [2], "we randomly sampled the signals over the time domain, the mean values of the electric field over the time are expected to be obtained after averaging", and the field shown in Ref. [2] is a mean value. Figure 2 of Ref. [1] shows a steady current density distribution, from which a pulseless corona current could be inferred according to Sato's equation. [Extracted from the article]

We quantitatively separate interface optical second harmonic generation (SHG) and electric-field induced second harmonic generation (EFISH) from hydrogenated amorphous silicon (a-Si:H) interfaces and bulk. Using a 1.51 eV probe laser, we measure SHG signals from indium tin oxide (ITO) ITO/a-Si:H/ITO sandwich structures and vary the electric fields in the a-Si:H layer using an applied voltage bias. The a-Si:H/ITO interfaces form back-to-back diodes. Because of finite optical penetration depth, SHG probes only the front diode. When the front diode is reverse biased, the EFISH contribution dominates the SHG signal and probes the electric field in the ∼30 nm adjacent to the interface. Through fitting of the SHG data, we find that in this near-interface region, the electric field is proportional to the square root of the applied bias. The fitting measures the interfacial ITO/a-Si:H built-in voltage to be ∼0.2 V. [ABSTRACT FROM AUTHOR]