Preparation and Properties of Gallium Phosphide Doped by Rare-Earth Elements

Abstract

GaP single crystals have been grown from 5at.% solution of P in Ga with (0.01-0.1)at.% of La, Sm or Gd as dopants. Electric properties, photoconductivity and luminescence of the crystals have been investigated by standard methods.Energy levels of impurities, mobility and concentration of current carriers have been determined in wide temperature region. It was shown that nitrogen (N) and other uncontrolled impurities present in the crystals due to some peculiarities of crystal growth. The intrinsic RE impurity luminescent spectra can be seen only together with spectra of excitons bounded on N traps. The evaluation of quantum eficiency for RE impurity made on the base of luminescence decay measurements gives the value close to 1. The interpretation of GaP:RE luminescence spectra is presented as intrashell transitions activated by bound exciton recombination as well as D-A and D-valency band transitions between some contaminating impurity (donor) and RE element (acceptor).

Long-Term Convergence of Bulk- and Nano-Crystal Properties

“…Let us discuss now the influence of long-term ordering of the dopants and defects on the optical and mechanical properties of GaP and its ternary analog CdIn 2 S 4 . The microhardness and dislocation density in these samples have been evaluated over many decades (Goriunova, 1960;Radautsan et al, 1969;Pushkash et al, 1978;Valkovskaya et al, 1984;Pyshkin, 1967). Taking into account the full 50-year timeframe makes an exact comparison difficult; therefore, only general trends are discussed here.…”

“…As can be seen, the relatively pure crystals have minimum microhardness. An increase in the impurity concentration in GaP crystals, with the dopants such as N, Bi, simultaneously N and Sm (Pyshkin et al, 1990a;Pyshkin, 1967), substituting for the host atoms (N, Bi) or occupying the interstitials in the crystal lattice (Sm), leads to an increase in microhardness for the long-term-ordered crystals. The same behavior of microhardness for freshly prepared and long-term ordered single crystals was observed for mono-atomic Si and binary InP, pure and doped by different impurities.…”

Introductory Chapter: Bound Excitons in Gallium Phosphide

“…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.…”

“…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.…”

“…It, obviously, has very useful and interesting properties for application in optoelectronics, nanoscience, and technology. [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).…”