НОВЫЕ НАПРАВЛЕНИЯ РАЗВИТИЯ ТЕХНОЛОГИИ ПРОИЗВОДСТВА УЛЬТРАФИОЛЕТОВЫХ СВЕТОДИОДОВ

The paper presents results of the development of ultraviolet light−emitting diodes based on GaN/AlGaN heterostructures grown on AlN substrates by chloride−hydride vapor phase epitaxy. The peak wavelengths are in the range of 360—365 nm with a spectral width of 10—13 nm; the output optical power of LED dies is 50 mW at 350 mA.Представлены результаты по созданию ультрафиолетовых светодиодов на основе гетеро-структур GaN/AlGaN, выращенных на подложках AlN методом хлоридно-гидридной эпитаксии. Пиковые длины волн находятся в диапазоне 360—365 нм, ширина спектральной кривой составляет 10—13 нм, выходная оптическая мощность чипов светодиодов — 50 мВт при токе 350 мА

Quality Assessment of Processed Graphene Chips for Biosensor Application

The quality of graphene intended for use in biosensors was assessed on manufactured chips using a set of methods including atomic force microscopy (AFM), Raman spectroscopy, and low-frequency noise investigation. It is shown that local areas of residues on the graphene surface, formed as a result of the interaction of graphene with a photoresist at the initial stage of chip development, led to a spread of chip resistance (R) in the range of 1–10 kOhm and to an increase in the root mean square (RMS) roughness up to 10 times, which can significantly worsen the reproducibility of the parameters of graphene chips for biosensor applications. It was observed that the control of the photoresist residues after photolithography (PLG) using AFM and subsequent additional cleaning reduced the spread of R values in chips to 1–1.6 kOhm and obtained an RMS roughness similar to the roughness in the graphene film before PLG. Monitoring of the spectral density of low-frequency voltage fluctuation (SU), which provides integral information about the system of defects and quality of the material, makes it possible to identify chips with low graphene quality and with inhomogeneously distributed areas of compressive stresses by the type of frequency dependence SU(f)