The history of LEDs: Losev's glow

The name of Oleg Vladimirovich Losev today is known only to a narrow circle of specialists. What a pity: his contribution to science, to the development of radio engineering is such that it entitles this ascetic scientist to the grateful memory of his descendants.

Pupil of the fifth grade of the real school of the pre-revolutionary Tver Oleg Losev quietly rummaged that evening in his half-secret home radio laboratory, which he equipped with money saved from school breakfasts and made another electric squeaker. And no one could have thought that in a modest polite boy who stood out among classmates with a deep understanding of physics, a love of experimentation, the personality of a purposeful researcher is formed.

It all began with a public lecture on wireless telegraphy, as they called radio at that time, which was delivered by the head of the Tver radio receiving station B. M. Leshchinsky. At fourteen, Oleg Losev makes the final choice: his calling is radio engineering.

For Losev, an accidental road meeting with the largest radio specialist of that time, Professor V.K. Lebedinsky, turned out to be great life luck. In the carriage of a commuter train, a venerable scientist and an enthusiastic young man met and became friends forever. Oleg often visited the Tver radio station of international relations, where Lebedinsky comes from Moscow for scientific advice.

There is a world war - the station is engaged in intercepting radio communications of the enemy. The pupil of V.K. Lebedinsky, lieutenant M.A. Bonch-Bruezich, a passionate propagandist of radio business, is in every possible way guarding the young radio amateur. In the home laboratory of Oleg, work is in full swing: coherrers are being tested, crystal detectors are being made.

The revolutionary year of 1917 came. Losev at this time is finishing high school. He dreams of becoming a radio engineer. But for this it is necessary to get a special education, and he submits documents to the Moscow Institute of Communications.

In 1918, an initiative group led by Bonch-Bruezich moved to Nizhny Novgorod, where the first radio engineering research institute in Soviet Russia, the Nizhny Novgorod Radio Laboratory (NRL), was created. V.K. Lebedinsky becomes chairman of the NRL Council and editor of the first national scientific radio journal "Telegraphy and Telephony Wirelessly" ("TiTbp"). NRL played a major role in the development of domestic radio technology.

Losev studied at the Institute of Communications for only one month and soon found himself in Nizhny Novgorod - in the circle of his teachers and patrons. Of course, it was not without active agitation by V.K. Lebedinsky. An unselfish, attentive teacher took responsibility for the education of a young man. Losev joined the research activities of laboratories engaged in the development of the latest radio equipment for that time.

Passion for wireless telegraphy in those years swept the whole world. A glass tube with iron filings, a coherrer, has already receded into history, and the long-mastered crystal detector ceased to satisfy the growing demands of radio operators. The era of the electronic lamp was approaching. However, there were extremely few of them, in fact, the only type of R-5 radio tube, and even that remained the limit of dreams of all obsessed with radio technology. Therefore, the urgent task of those years was the improvement of the crystal detector. These devices worked very unstable.

Losev checks the cleanliness of the surface and the external structure of the crystals, in various modes, studies the current-voltage characteristics of the detectors and evaluates the factors influencing them.

The young researcher does not leave the Nizhny Novgorod laboratory for days: during the day he conducts experiments, at night he takes his “place” on the third floor, before going to the attic, where his bed is, and his coat serves as a blanket. That was the "comfort" of the early 1920s.

Studying the current – ​​voltage characteristics of the detectors, Losev noticed that some samples have a rather strange curve, including the incident section. They detect just as unstable, but something tells Oleg that he is on the way to a solution. At the end of 1921, during a short vacation in Tver, Losev continued his experiments in his youthful laboratory. Again he takes zincite and charcoal from the old lamp, begins to test the detector. What is it? In the headphones, some distant station is transmitting Morse code cleanly and loudly. This has not happened before ... So - the reception is not detector!

This was the first heterodyne device based on a semiconductor device. The resulting effect is essentially a prototype of the transistor effect. Losev was able to identify a short falling section of the characteristic that can lead to self-excitation of the oscillatory circuit. So, on January 13, 1922, a 19-year-old researcher made an outstanding discovery. They will understand and theoretically describe it much later, but for now - the practical result: radio operators all over the world get a simple detector receiver that works no worse than an expensive tube local oscillator, without bulky power batteries, without scarce electronic tubes and complicated setup.

Losev tried a lot of materials as a working crystal. The best was the refined zincite obtained by fusion in an electric arc of natural zincite crystals or pure zinc oxide. A steel needle served as a contact hair.

The description of a semiconductor receiver with a generating crystal appeared in print - this was the last word in radio engineering. Soon, Oleg developed a number of radio circuits with crystals and wrote a brochure for radio amateurs with detailed characteristics of the receivers and recommendations for the manufacture of crystals.

Immediately after the first publication, Losev’s discovery attracted the close attention of foreign experts. The American Radio News magazine exclaimed: “The young Russian inventor O. V. Losev transferred his invention to the world without taking a patent on it!” One of the French magazines wrote more tactfully: "... Losev announced his discovery, thinking primarily about his friends - radio amateurs all over the world." Losev’s receiver was named “Kristadin”, which meant a crystal local oscillator. Kristadin received weak signals from distant transmitting stations, increased the selectivity of reception, and weakened the level of interference.

A wave of amateur radio engulfed the youth of the country, and the “Cristina Dyna Fever" began. Zincite was hard to get, they tried what came to hand - any crystal. Mass research brought another find - galena (artificial lead shine), it worked well, and there were a lot of it. Later, scientists will argue: why, in the 20s, the transistor was not open? Why did the gifted researcher, not having exhausted all the possibilities of his discovery, suddenly leave it? What made us turn the work in a different direction? The answer is ...

In 1923, experimenting with a detecting contact based on a carborundum – steel wire pair, Oleg Losev discovered a faint glow at the junction of two dissimilar materials. Previously, he did not observe such a phenomenon, but before that, other materials were used. Carborundum (silicon carbide) was tested for the first time. Losev repeated the experiment - and again a translucent crystal under a thin steel tip lit up. So, a little over 60 years ago, one of the most promising discoveries of electronics was made - electroluminescence of a semiconductor junction. Losev discovered the phenomenon by chance or there were scientific prerequisites, now it is difficult to judge.One way or another, but a young talented researcher did not pass by an unusual phenomenon, did not classify it as a random noise, on the contrary, paid close attention, and guessed that it was based on a principle still unknown to experimental physics.

The luminescence was repeatedly studied on various materials, in different temperature conditions and electrical conditions, was examined under a microscope. It became increasingly apparent to Losev that he was dealing with a discovery. “It is more likely that a completely peculiar electronic discharge occurs here, which, as experience shows, does not have glowing electrodes,” he writes in another article. So, the novelty, the unknown to science of open glow for Losev is undeniable, but there is no understanding of the physical essence of the phenomenon.

Several versions were formulated regarding the physical causes of the open glow. He expresses one of them in the same article: “Most likely, the crystal glows from electronic bombardment similarly to the glow of various minerals in the fruit tubes”. Later, checking this explanation, Losev places various crystals in a cathode-luminescent tube and, when irradiated, compares the spectra and intensity of the emitted light with similar characteristics of the detector glow. A significant similarity is found, but the question of a clear understanding of the physics of the phenomenon, according to Losev, remains open.

The scientist focuses all his efforts on a deep and detailed study of the luminous carborundum detector.

In No. 5 of TiTbp magazine for 1927, a large article appears, “Luminous Carborundum Detector and Detection with Crystals,” in which the experimenter writes: “Two types of luminescence can be distinguished ... luminescence! "A greenish-blue, bright little dot and a luminescence II, when a significant surface of the crystal fluoresces brightly." Only a few decades later, it turns out that as a result of the random introduction of atoms of other elements in the carborundum crystal lattice, active centers were created in which intense recombination of current carriers occurred, as a result of which light energy quanta were ejected.

Experimenting with different types of crystals and different contact wires, O. V. Losev makes two important conclusions: the glow occurs without heat, that is, it is “cold”, the inertia of the appearance and decay of the glow is extremely small, that is, it is practically inertialess. Now we know: these characteristics of the glow, noted by Losev in the 20s, are the most important for today's LEDs, indicators, optocouplers, infrared emitters.

The physical essence of the glow is still unclear, and O. V. Losev persistently seeks an explanation of the physics of the phenomenon. Soon he makes one important observation, closer to understanding the essence of the process: “Under a microscope, you can clearly see that the glow occurs when the contact wire touches sharp edges or fractures of the crystal ...”, that is, light is generated on crystalline defects. Technical reports for 1927, stored in the archives of the V. I. Lenin NRL, confirm how thoroughly the study of the luminous carborundum detector was conducted. The influence of a strong magnetic field, ultraviolet radiation and x-rays was studied; behavior in various media — ionization of the air surrounding the glow was tested, and thermal emission of various minerals was studied. Erroneous versions disappear one after another, and step by step the accumulation of valuable knowledge proceeds. Losev himself prepares various varieties of carborundum for experiments, mounts test facilities, saws and sharpenes metal, takes measurements, keeps working journals - all by himself, from the idea to the final results.

Losez's studies on electroluminescence have received wide response and recognition abroad.His works were reprinted by foreign magazines, and the discovery received the official name - “Losev's Glow”. Both abroad and we have made attempts to use it in practice. Losev himself received a patent for the “light relay” device, but the poor development of solid state theory at that time and the almost complete absence of semiconductor technology did not allow the scientist to find practical applications for electroluminescence work. In essence, they related to the problems of the future, and the turn came to them only after 20-30 years.

The practical use of the effect of the glow of Losev began in the late fifties. This was facilitated by the development of semiconductor devices: diodes, transistors, thyristors. Not only semiconductor elements were information display elements - bulky and unreliable. Therefore, in all countries developed in scientific and technical terms, intensive development of semiconductor light-emitting devices was carried out.

The first of them began to be commercially available phosphide-gallium red LED. Following him appeared a silicon carbide diode with yellow radiation. In the sixties, physicists and technologists created green and orange LEDs. Finally, at the beginning of the current decade, a blue LED was obtained on the antimonide. In parallel, there was a search for new technological methods, semiconductor materials and transparent plastics. As a result of intensive work, the brightness of the devices was significantly increased, various types of segmented digital alphanumeric indicators, matrix indicators and linear scales were developed. Devices with a changing glow color, as well as various types of LED mnemonic emitters that highlight a variety of geometric shapes: a rectangle, triangle, circle, etc. Recently, a new class of devices has emerged - modules of flat solid-state screens from which you can assemble mosaic screens and new generation scoreboard.

The scientist is ahead of his contemporaries. His merit is not only in the discovery of the detector glow, but mainly in the fact that with his research he raised the problem so sharply that the continuation of work in this area became inevitable. So, the intuition and perseverance of O. V. Losev is due to the emergence of a new direction of electronics - semiconductor optoelectronics, which has a great future.

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