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1. Heterogeneously integrated waveguide-coupled InGaAs/InP SACM avalanche photodiodes on silicon nitride for 1550 nm

   https://doi.org/10.1364/OE.587067  

   Fatema, Tasneem; Xuan, Maxwell Wei; Singaraju, Prerana; Kim, Taegeon; Circir, Kubra; Guo, Xiangwen; Herrera, Daniel J; Campbell, Joe C; Dagenais, Mario; Beling, Andreas (January 2026, Optics Express)

   The silicon nitride/silicon (Si₃N₄/Si) photonic platform has attracted significant interest due to its ultra-low-loss waveguides and high-performance optical components. Progress in heterogeneous integration has enabled the development of active photonic devices on Si₃N₄, including PIN waveguide photodiodes. However, to the best of our knowledge, an integrated avalanche photodiode (APD) with internal gain operating at 1550 nm wavelength has not been demonstrated to date. Here, we report on the design, fabrication, and characterization of InP/InGaAs separate absorption, charge, and multiplication (SACM) APDs heterogeneously integrated on Si₃N₄waveguides. Our APDs have a dark current of 5 nA near breakdown at room temperature, a multiplication gain of 166, and an internal responsivity of 0.61 A/W at unity gain. The 3-dB bandwidth is 4.2 GHz, and we demonstrate open eye diagrams at 7.5 Gbps. 

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2. Dual-Sacrificial-Layer Wet Etching for Transfer Printing of InP-Based Antimony-Containing Materials

   https://doi.org/10.1149/2162-8777/ae10de  

   Xia, Yongkang; Nikor, Sk_Shafaat Saud; Gajowski, Nathan; Lee, Seunghyun; Muduli, Manisha; Noh, Siyun; Nallamothu, Naga Swetha; Adams, Rachel L; Reano, Ronald M; Ringel, Steven A; et al (October 2025, ECS Journal of Solid State Science and Technology)

   We report a dual-sacrificial-layer-based lateral wet etching scheme for the heterogeneous integration of InP-based antimony-containing GaAsSb, InGaAsSb, and AlGaAsSb materials on foreign substrates such as Si. For a proof-of-concept demonstration, only ternary lattice-matched GaAsSb is investigated here. Two wet etchants based on HCl and HF are employed, and the associated results are compared in terms of etch rates, selectivity, and surface roughness. A dual sacrificial layer comprising lattice-matched InAlAs and InP was also employed in this study, and it allows for effective etching by HCl as confirmed by surface smoothness and high selectivity. During the transfer printing process, lateral wet etching of the sacrificial layer is accomplished in as little as 30 min to produce a clean etch profile for a coupon size of 300 × 300 μm. The successful GaAsSb transfer on silicon substrates is then vetted by both material and device level characterizations, suggesting satisfactory bonding due to clean and smooth wet etching profiles. The developed wet etching technique would facilitate next-generation InP-based electronic and optoelectronic devices. 

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3. Using Highly Functional Cr ₂ O ₃ Interfacial Layer to Enhance the Electrical Performance of Au/InP Schottky Diodes

   https://doi.org/10.1002/aelm.202500050  

   Krupa, Sreedhar_Gari Sai; Reddy, Dandala Surya; Lakshmi‐Narayana, Ambadi; Rajagopal_Reddy, Varra; Ramana, Chintalapalle V (August 2025, Advanced Electronic Materials)

   Abstract Herein, the significant impact of the spin‐coated Cr₂O₃interface layer on the electrical properties and performance characteristics of Au/undoped‐InP (Au/InP) Schottky diodes (SD) is reported. The material characterization of spin‐coated Cr₂O₃films using a wide variety of analytical techniques, namely, atomic force microscopy, field emission scanning electron microscope, X‐ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy, indicate the formation of hexagonal phase, nanocrystalline, and stoichiometric Cr₂O₃on InP. Optical absorption measurements reveal a bandgap of ≈3.5 eV. In‐depth analyses and detailed measurements of current‐voltage (I–V) and capacitance‐voltage (C‐V) employed to assess the interface characteristics and electrical performance of the Au/InP (SD) versus Au/Cr₂O₃/InP (MIS) devices. Compared to SD, MIS revealed superior rectifying properties. Indicating that the Cr₂O₃interface layer significantly influences the barrier height (Φ_BH) of SD, the estimated Φ_BH(0.64 eV (I–V)/0.86 eV (C‐V)) is higher than that of SD (0.57 eV (I–V)/0.67 eV (C‐V)). In addition, Cheungs and Nordes' methods are used to obtain the Φ_BH, ideality factor (n), and series resistance (R_S). The equivalent Φ_BHvalues obtained from current–voltage, Cheungs, and Nordes methods demonstrate stability and dependability in addition to validating their superior characteristics of MIS devices. The interface state density (N_SS) for MIS is lower than the SD's, indicating that the effectiveness of Cr₂O₃layer significantly reduces N_SS. Analyses to probe the mechanism demonstrate that, in SD and MIS, the Schottky emission controls the higher bias area, while the Poole‐Frenkel emission dominates the reverse conduction mechanism at the lower bias region. The present work convincingly demonstrates the potential application of the Cr₂O₃interfacial layer in delivering the enhanced performance and contributes to the progression of electrical devices for emerging electronics and energy‐related applications. 

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4. Epitaxial Growth of Large‐Scale 2D CrTe₂ Films on Amorphous Silicon Wafers With Low Thermal Budget

   https://doi.org/10.1002/adma.202311591  

   Zhang, Xiaoqian; Li, Yue; Lu, Qiangsheng; Xiang, Xueqiang; Sun, Xiaozhen; Tang, Chunli; Mahdi, Muntasir; Conner, Clayton; Cook, Jacob; Xiong, Yuzan; et al (June 2024, Advanced Materials)

   Abstract 2D van der Waals (vdW) magnets open landmark horizons in the development of innovative spintronic device architectures. However, their fabrication with large scale poses challenges due to high synthesis temperatures (>500 °C) and difficulties in integrating them with standard complementary metal‐oxide semiconductor (CMOS) technology on amorphous substrates such as silicon oxide (SiO₂) and silicon nitride (SiN_x). Here, a seeded growth technique for crystallizing CrTe₂films on amorphous SiN_x/Si and SiO₂/Si substrates with a low thermal budget is presented. This fabrication process optimizes large‐scale, granular atomic layers on amorphous substrates, yielding a substantial coercivity of 11.5 kilo‐oersted, attributed to weak intergranular exchange coupling. Field‐driven Néel‐type stripe domain dynamics explain the amplified coercivity. Moreover, the granular CrTe₂devices on Si wafers display significantly enhanced magnetoresistance, more than doubling that of single‐crystalline counterparts. Current‐assisted magnetization switching, enabled by a substantial spin–orbit torque with a large spin Hall angle (85) and spin Hall conductivity (1.02 ×  10⁷ℏ/2e  Ω⁻¹  m⁻¹), is also demonstrated. These observations underscore the proficiency in manipulating crystallinity within integrated 2D magnetic films on Si wafers, paving the way for large‐scale batch manufacturing of practical magnetoelectronic and spintronic devices, heralding a new era of technological innovation. 

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5. Stability of the Y ₂ O ₃ –SiO ₂ system in high‐temperature, high‐velocity water vapor

   https://doi.org/10.1111/jace.16915  

   Parker, Cory G; Opila, Elizabeth J (April 2020, Journal of the American Ceramic Society)

   Abstract High‐temperature, high‐velocity water vapor (steam‐jet) exposures were conducted on Y₂O₃, Y₂SiO₅, Y₂Si₂O₇, and SiO₂for 60 hours at 1400°C. Volatility of Y₂O₃was not observed. Phase‐pure Y₂SiO₅exhibited SiO₂loss forming Y₂O₃and porosity. A mixed porous and dense Y₂SiO₅layer formed on the surface of Y₂Si₂O₇due to SiO₂depletion. The mechanisms and kinetics of the reaction between SiO₂and H₂O(g) to form Si(OH)₄(g) from Y₂SiO₅, Y₂Si₂O₇, and SiO₂are discussed. 

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