Semiconductor Photodetectors : Optical Spectrometry

The exponential increase of the Internet of Things (IoTs) has revolutionized lives, but it has also resulted in massive resource consumption and environmental pollution. In conjunction with Green IoTs (GioTs), there is a parallel effort to create highly sensitive devices by device design to conserve power. Furthermore, numerous applications require deciphering information from very weak optical signals, such as from radiation, medical imaging, industrial non-destructive testing, quantum technologies, astronomy, and various other such routine measurements. It is necessary to design photodetectors with high photosensitivity using various technological innovations to reduce the noise level, such as with two inversely directed barriers, as proposed by the authors, in which the currents of devices mutually compensate each other and create low dark current with high photosensitivity thresholds. The implementation of internal amplification of photocurrents in them can provide high photosensitivity. The book presents the mechanism for the injection amplification of the photocurrent in devices based on cadmium telluride and silicon with a high-resistance sublayer, as well as the study of creating highly sensitive devices, that are resistant to radiation of optical and X-ray ranges of electromagnetic waves. Particular attention is drawn to the mutual compensation process for photocurrents arising in opposite potential barriers covering the layer during longitudinal absorption of radiation in the sublayer. Using structures on the base cadmium telluride and silicon, as an example, the phenomenon of a change in the sign of the spectral photocurrent and the possibilities of wave measurement is provided by this phenomenon. Photoelectronic processes occurring in these semiconductor structures are investigated, and expressions are obtained that relate the parameters of optical radiation and the structure. The algorithm developed using these expressions is based on a new spectral analysis mechanism, which is implemented to prepare inexpensive, reduced dimensions with the need for less materials, and energy-intensive devices. All this is considered in the context of solving urgent problems of quantitative remote identification of the components of an optically transparent medium. The global spectral analysis market is focused on the development of semiconductor photodetectors with spectral-selective sensitivity for spectral analysis. The use of such a photodetector in spectrometry will eliminate the use of opticalmechanical systems due to the new physical principle used in it and will ensure high resolution and reliability of spectrum recording. As environmental threats become increasingly unpredictable, there is also a growing need to develop remote spectral analysis, identification, and assessment of substances in air, water, and food, assessment of the effects of substances on humans, animals, and vegetation, and detection and elimination of pollution sources. Here, the spectral analysis of the electromagnetic radiation transmitting the information from the object with the help of primary sensors is essential.

The scientific monograph of co-authors Surik Khudaverdyan and Ashok Vaseashta entitled Semiconductor Photodetectors: Optical Spectrometry contains the results of multi-year research dedicated to the discovery of the photocurrent injection amplification mechanism in silicon and cadmium telluride samples in the optical (silicon and cadmium telluride) and X-ray ranges resistant to action (cadmium telluride) to the development of ultrasensitive devices. Special attention was paid to the photocurrent compensation processes generated in the opposing potential barriers covering the layer during the longitudinal absorption of the beam in the substrate. In silicon and cadmium telluride structures with opposing potential barriers, the phenomenon of spectral photocurrent sign change and the wavemetric possibilities provided by it, the short and long wavelength maxima of the spectral photocurrent and their unusually high photosensitivity were revealed for the first time. A new mechanism spectral analysis was used in the algorithm obtained by mathematical modeling of photoelectronic processes in structures. This allows for the development of photospectrometers that lack the diffraction gratings, prisms, photodetector arrays, and precise optical and mechanical devices found in traditional photospectrometers.

All of that was considered in the perspective of quantitative remote identification of components of optically transparent media and facing modern challenges.

I believe that the monograph is an important contribution to the field of semiconductor photodetectors, and it is necessary and useful for undergraduates, graduate students, and the scientific community in the field.

Prof. Dr. Hovik Bagdasaryan, National Polytechnic University of Armenia, Email: [email protected]

-

Authored by Surik Khudaverdyan and Ashok Vaseashta, the scientific monograph titled "Semiconductor Photodetectors, Optical Spectrometry" is dedicated to the development and research of photosensors with advanced functional capabilities designed to address modern challenges. The authors have successfully developed silicon photosensors based on a novel physical principle for photocurrent processing, allowing spectrometric properties to be achieved through an innovative algorithm. This type of photosensor eliminates the need for optical-mechanical systems while ensuring high resolution and reliable spectrum registration.

The authors have also developed photosensors based on cadmium tellurite and silicon that enable photocurrent injection amplification in both the visible and X-ray spectrums. These structures exhibit very low dark currents, which ensures high photosensitivity and the capability to detect weak signals.

The findings presented in the monograph hold significant potential for remote spectral analysis of harmful substances, enabling their identification and quantitative telemetry. This includes assessing the impact of these substances on humans, animals, vegetation, air, water, and food sources, as well as identifying and mitigating pollution sources.

I am confident that the authors'' innovations will contribute valuable tools to address the environmental, biological, healthcare, and other pressing challenges facing humanity.

This scientific monograph contains numerous advancements in semiconductor photonics and is a valuable resource for students, postgraduates, and the broader scientific community within this field.

Prof. Dr. Karen Hambaryan, Yerevan State University, Armenia, Email: [email protected]