Realizing the insulator-to-metal transition in Se-hyperdoped Si via non-equilibrium material processing

Abstract

Abstract. We report on the insulator-to-metal transition in Se-hyperdoped Si layers driven by manipulating the Se concentration via non-equilibrium material processing, i.e. ion

First principles simulations of microscopic mechanisms responsible for the drastic reduction of electrical deactivation defects in Se hyperdoped silicon

“…The complexes formed by one substitutional Se nearest-neighbour (NN) to a Si vacancy, Se Si − V Si , and the Se interstitial, I Se , in hexagonal or in tetrahedral position, have significantly higher formation energy than the other complexes investigated; for x 0.45 at. % the formation energy of these complexes is smooth, and consequently, the formation of these complexes is unlikely, explaining the dramatic reduction of interstitial Se at these concentrations as experimentally detected in Se hyperdoped Si [32,33]. A similar mechanism has been also found in Te hyperdoped Si [6] (by comparing ∆E F orm D of I Te , Te Si , Te Si − Te Si ).…”

“…We focused our attention in complexes involving substitutional Se, motivated by the experimental evidence that at high chalcogen concentration in Si (i.e. concentration comparable or higher than x c , the critical concentration at which the IMT occurs) the substitutional impurities are the predominant type of defect (at least for Se [32,33] and Te [6]), a fact that can be explained on the basis of first principles calculations by the significantly higher formation energy of chalcogen in interstitial position than the substitutional ones, as shown in Ref. [6] for The relative concentrations of the defects I Se , and of the complex (Se Si ) 1 − V Si (i.e.…”

Breaking the Doping Limit in Silicon by Deep Impurities

“…The critical angle ψ 1/2 represents the half width of the angular scans at half maximum between χ min and 1 (full width at half maximum of the angular scan spectrum), and it is related to the displacement vector of substitutional atoms [15]. F. Displacement estimation 24 The RBS/C angular scans shown in FIG. S4 for Si and Te suggest that the Te atoms may be displaced from the ideal substitutional Si lattice sites.…”

“…This makes chalcogens good prospects to be used for overcoming the doping limit in Si. Particularly, one puzzling observation in chalcogen-doped Si is that the electron concentration increases linearly with the dopant concentration while the substitutional fraction remains almost constant [23,24]. For traditional shallow-level dopants, interstitials, inactive clusters and precipitates often become more energetically favorable as the dopant concentration increases, e.g.…”

Critical behavior of the insulator-to-metal transition in Te-hyperdoped Si

“…There are very few and relatively recent experimental studies of the IMT with deep-level impurities, such as chalcogens (S, Se, and Te) in Si [13][14][15][16]. According to Mott's theory the IMT is expected to occur at much higher concentrations (ncrit >> 10 18 cm -3 ) than for shallow donors, since electrons are much more tightly bound with a significantly reduced radius.…”