The advancement of ultrafast photonics and optoelectronic devices necessitates the exploration of new materials with optical and chemical stability to implement practical applications. Layered quaternary metal-thio/selenophosphate has attracted much interest over the past few years. Ferroelectric CuInP 2 S 6 (CIPS) is an emerging material that belongs to this family. When synthesized with Cu deficiencies, CIPS forms self-assembled in-plane heterostructures, which in turn exhibit properties that are both compositionally and thermally dependent. These characteristics can be explored for applications in nonlinear optoelectronic and photonic devices. Herein, we study the second and third order nonlinear optical behavior of Cu 0.33 In 1.30 P 2 S 6 bulk heterostructure. We observed large two photon induced nonlinear absorptions and self-defocusing at 1032 nm pulsed laser excitation using the Z-scan technique. Furthermore, we identified a polarization-dependent second harmonic signal and determined the laser-induced optical damage threshold. Our observations allow for the designing of optoelectronic and ultrafast photonic devices based on these materials.

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In this work, we demonstrate for the first time two-junction ultraviolet light emitting diodes enabled by transparent tunnel junctions. Low voltage-drop tunnel junctions were realized in Al0.3Ga0.7N layers through a combination of high doping and compositional grading. Capacitance and current-voltage measurements confirmed the operation of two junctions in series. The voltage drop of the two-junction LED was 2.1 times that of an equivalent single-junction LED, and the two-junction LED had higher external quantum efficiency (147%) than the single junction.

We demonstrate a method to achieve selectively patterned Mg-doped GaN layers using hydrogen drive-in through plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (SiNx) films. Activated Mg-doped GaN layers were selectively deactivated by patterned PECVD SiNx films with low-temperature annealing and showed high-resistive behavior. Spatially resolved photoluminescence measurements were used to optically verify the deactivation of Mg acceptors and showed distinct features corresponding to activated and deactivated Mg in GaN. The method suggested here provides a simple and effective method to achieve patterned Mg-doped GaN regions without thermal and plasma damage, which could cause degradation of device performance. The proposed method could provide a way to achieve future high-performance GaN lateral and vertical devices that rely on laterally patterned doping.