Excitonic Crystal and Perfect Semiconductors for Optoelectronics

Abstract

This chapter demonstrates the growth of perfect and contamination-free gallium phosphide (GaP) crystals and discusses the influence of crystallization conditions on their quality and properties. The long-term ordered and therefore close to ideal crystals replicates the behavior of the best nanoparticles exhibiting pronounced quantum confinement effect. These perfect crystals are useful for application in topquality optoelectronic devices as well as they are a new object for the development of fundamentals of solid state physics. Since samples of gallium phosphide doped by nitrogen (GaP:N) were originally prepared by the author in the 1960s, followed by the introduction of the excitonic crystal concept in the 1970s, the best methods of bulk, film and nanoparticle crystal growth have been elaborated. The results of semi centennial evolution of GaP:N properties are compiled here. Novel and useful properties of perfect GaP including its stimulated emission, very bright and broadband luminescence at room temperature were observed. These results provide a new approach to selection and preparation of perfect materials for optoelectronics and a unique opportunity to realize a new form of solid-state host-the excitonic crystal as high intensity light source with expected low threshold for the generation of non-linear optical phenomena. Using the example of GaP here is proposed as a cheap, resource-saving and impactful way to develop optoelectronics through a special transformation of an ordinary semiconductor into the base material for various device structures.

Excitons and the Positronium Negative Ion: Comparison of Spectroscopic Properties

“…These properties include enhanced stimulated emission and very bright and broadband luminescence at room temperature. With such development of bound excitons as short-lived analogs of atoms under some specific rules, it is also important to mention here that the emission spectra of representatives of exciton and positronium negative ion families can be realized from the earlier articles [104][105][106][107][108]. These articles support the usefulness of such comparisons of spectroscopic properties of excitons and the positronium negative ion.…”

Properties of GaP Studied over 50 Years

“…Jointly with Refs. [25,26,[31][32][33][34], this review provides a generalization of the results on these long-term observations of luminescence, absorption, Raman light scattering, and microhardness of the bulk single crystals in comparison with the same properties of the highquality GaP nanocrystals. It is shown that the combination of these characterization techniques elucidates the evolution of these crystals over the course of many decades.…”

Introductory Chapter: Bound Excitons in Gallium Phosphide

“…In this way, decades pass before the lattice component occupies the exactly correct position in the crystal lattice, diffusing inside it at the storage temperature, from the place where it was at the time of the onset of cooling of a mixture of GaP, necessary for the onset of deposition and further growth of pure or doped crystals (see details in [1][2][3][4][5][6][7][8]). Naturally, most crystal manufacturers are reluctant to wait for improvements in the structure and properties of imperfect crystals, as this process is extremely slow.…”

“…We have been growing and exploring gallium phosphide [1][2][3][4][5][6][7][8] for more than a half a century, a process of experimenting, analysis and observation which resulted in unique material reflecting previously unexplored properties of excitons and new prospects for the use of GaP, which could be very interesting for application in the electronic industry.…”

“…[1] in comparison with the luminescence of GaP nanoparticles and GaP/polymer nanocomposites [2,3]. Prepared by us, nanoparticles [5,7] were stored as dry powder (spectrum 2) or suspension in a liquid (spectrum 3).…”