Photon assisted Lévy flights of minority carriers in n-InP
نویسندگان
چکیده
We study the photoluminescence spectra of n-doped InP bulk wafers, both in the reflection and the transmission geometries relative to the excitation beam. From the observed spectra we estimate the spatial distribution of minority carriers allowing for the spectral filtering due to reabsorption of luminescence in the wafer. This distribution unambiguously demonstrates a non-exponential drop-off with distance from the excitation region. Such a behavior evidences an anomalous photon-assisted transport of minority carriers enhanced owing to the high quantum efficiency of emission. It is shown that the transport conforms very well to the so-called Lévy-flights process corresponding to a peculiar random walk that does not reduce to diffusion. The index g of the Lévy flights distribution is found to be in the range g1⁄4 0:64–0.79, depending on the doping. Thus, we propose the high-efficiency direct-gap semiconductors as a remarkable laboratory system for studying the anomalous transport. & 2012 Elsevier B.V. All rights reserved.
منابع مشابه
Temperature controlled Lévy flights of minority carriers in photoexcited bulk n-InP
We study the spatial distribution of minority carriers arising from their anomalous photon-assisted diffusion upon photo-excitation at an edge of n-InP slab for temperatures ranging from 300K to 78K. The experiment provides a realization of the “Lévy flight” random walk of holes, in which the Lévy distribution index γ is controlled by the temperature. We show that the variation γ(T ) is close t...
متن کاملLÉVY FLIGHT OF HOLES IN InP SEMICONDUCTOR SCINTILLATOR
High radiative efficiency in moderately doped n-InP results in the transport of holes dominated by photon-assisted hopping, when radiative hole recombination at one spot produces a photon, whose interband absorption generates another hole, possibly far away. Due to “heavy tails” in the hop probability, this is a random walk with divergent diffusivity (process known as the Lévy flight). Our key ...
متن کاملRadiation efficiency of heavily doped bulk n-InP semiconductor
Recombination of minority carriers in heavily doped n-InP wafers has been investigated using spectral and time-resolved photoluminescence at different temperatures. Studies of the transmitted luminescence were enabled by the partial transparency of the samples due to the Moss–Burstein effect. Temporal evolution of the transmitted luminescence shows virtually no effect of surface recombination b...
متن کاملDirect observation of Lévy flights of holes in bulk n-doped InP
We study the photoluminescence spectra excited at an edge side of n-InP slabs and observed from the broadside. In a moderately doped sample the intensity drops off as a power-law function of the distance from the excitation—up to several millimeters—with no change in the spectral shape. The hole distribution is described by a stationary Lévy-flight process over more than two orders of magnitude...
متن کامل