[2][3][4] He observed light emission from carborundum point-contact junctions, constructing a light-emitting diode (LED), did the first research on them, proposed the first correct theory of how they worked, and used them in practical applications such as electroluminescence.

[3][4][5] He explored negative resistance in semiconductor junctions, and was first to use them practically for amplification, building the first solid-state amplifiers, electronic oscillators, and superheterodyne radio receivers, 25 years before the invention of the transistor.

[1][3] Although he managed to attend a few classes, he remained throughout his life a self-taught scientist who never got to complete a college education, never had the support of a collaborator or research team, and never held a position higher than a technician.

[3] When Nizhny Novgorod was shut down in 1928, he transferred along with many of the research staff to the Central Radio Laboratory (CRL) in Leningrad (St.

[1] In radio receivers, crystal detectors were often forward-biased with DC current from a battery to make them more sensitive rectifiers.

[3] Although this effect had been noticed in 1907 by British Marconi engineer Henry Joseph Round, he had just published a brief two paragraph note on it.

[3][5][8] At the time, the prevailing theory of point contact junctions was that they worked by a thermoelectric effect,[5] possibly due to microscopic electric arcs.

[5][8] He theorized correctly that the explanation of the light emission was in the new science of quantum mechanics,[5] speculating that it was the inverse of the photoelectric effect explained by Albert Einstein in 1905.

[4][16][17][18][19][20] Losev was the first to exploit negative resistance diodes practically; he realized that they could serve as simpler, cheaper replacements for vacuum tubes.

[1] He used these junctions to build solid-state versions of amplifiers, oscillators, and TRF and regenerative radio receivers, at frequencies up to 5 MHz, 25 years before the transistor.