CN1033294C - Optical memory material - Google Patents

Abstract

The present invention discloses a structural design of optical information recording material and a preparation method. The present invention adopts a sandwich material design and forms an electron donor layer and an electron capture layer that are mutually in alternate arrangement, wherein electrons excited in the donor layer can be transferred far away from a donor center through the diffusion of an external field, so that the electrons are captured by a trap center in the capture layer, and the efficiency of writing information is improved thereby. After the action of both writing and the external field stops, the electrons in the capture layer are difficult to spontaneously return to the original state, so that the stability of information storage is improved.

Description

Optical memory material

The invention belongs to optical storage material, specifically, relate to a kind of optical storage material structural design.

The electron capture technology that is used for optical storage is the [J.Lingmayer that the Optex company of Maryland, USA Luo Keweier proposes at late nineteen eighties, Solid state Technology/August, 135 (1988)], material therefor is certain II-VI compounds of group vapor-deposited film of rare earth ion codope.A kind of rare earth provides electronics as electron donor in the material, and another kind is the trap trapped electron.Capture for the Electron absorption photon transition at body center to high-energy state and by the trap center, this process is writing and storing of information.Under the infrared light effect, the electronics in the trap is released and returns the ground state ballistic phonon again, and this process is reading of information.This is that a kind of heat that do not produce does not need the photon process that heats yet, therefore, it than present magneto-optic and mutually faster the and medium of technology read and write cycle life and be tending towards unlimited.The light intensity that this class material of while writes and reads in very large range is fabulous linearity, and during as analog record or the use of many level digitals recording medium, comparable existing CD improves several times of storage density.

But the material that adopts at present design all is a single layer structure, is distributed in in one deck promptly for body center and trap center simultaneously.Capture at the trap center that is close on every side most possibly after the Electron absorption photon of giving the body center is excited, because close together, it is not little that the electronics at trap center still is by hot activation that the tunnelling mode returns to the probability at body center again, therefore time information memory is short, at room temperature only just disappears in 20 days.By the same token, it is lower to write efficient.

The structural design that the purpose of this invention is to provide a kind of electron capture optical storage membraneous material, the optical storage membraneous material of this structure can improve the stabilization time of information stores and be incorporated into efficient.

To achieve these goals, the present invention adopts the sandwich design, electron donor center and electron capture center are not existed simultaneously with in one deck, form electron donor layer and the electron trapping layer alternately arranged, every layer thickness is at 100～1000 , total number of plies is at 2～100 layers, and applying direct current electric field when light writes adds the DC electric field opposite with writing electric polarity when reading.

Owing to adopt sandwich construction, give electrons excited in the body layer because outer field action can be transferred to the body center at a distance, so that the trap center (also claiming the acceptor center) that is captured in the layer captured.After electronics was captured by the acceptor center, electronics can given pace be got back to the body center.This speed is with relevant to body one acceptor spacing, and it satisfies

K=AeXp (2R _DA/ R _O) R wherein _OBe van der Waals radius, R _DAFor giving body and acceptor spacing, A is a constant. in single layer structure, mean distance is R between body and acceptor if give, and then information erasing speed is

K ₁＝Aezp(-2R _DA/R _O)。

In sandwich construction, establish structural parameters as shown in Figure 1, the shadow region is the electron donor layer among the figure, white space is the electron accepter layer.Suppose that the electron concentration in the receptive layers does not become Δ n with X, electronics is captured mean speed by receptive layers again and is so ${\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="C9410687300042.png"\; state="\{\{state\}\}">K</figure-callout>}}_2=\frac{\underset{X_D}{\overset{X_A}{\&Integral;}}\mathrm{Aexp}(-2X/R_O)\mathrm{\&Delta;ndX}}{\underset{X_D}{\overset{X_A}{\&Integral;}}\mathrm{\&Delta;ndx}}=\frac{A\&CenterDot;{R_{\mathrm{oe}}}^{-2X_D/R_D}}{2(X_A-X_D)}$

Following formula hypothesis X _A＞＞X _D, omitted e _D ^-2X/ _O ^R]

Show that information storage stability is proportional to capture layer thickness.If X _D=R, design is subjected to body thickness much larger than van der Waals radius, then

K ₂/K ₁＝R _O/2(X _A－X _D)＜＜1

Illustrate that sandwich construction improves stability of stored data than single layer structure.

Light pulse electrons excited in the heart from give body can be captured by the acceptor center, also can be captured for the body center again.The recombination rate that makes acceptor center and electronics is R _A, electronics is R to bulk recombination rate again _D, so in single layer structure, the ratio that light pulse electrons excited is captured by the acceptor center is R _A/ R _A+ R _DIn sandwich construction, add DC electric field E simultaneously when acting on a light pulse, electronics will spread and drift motion simultaneously, and satisfies following equation $\frac{\&PartialD;\mathrm{\&Delta;n}}{\&PartialD;l}-\mathrm{Dn}\frac{{\&PartialD;}^{\&prime;}\mathrm{\&Delta;n}}{{\&PartialD;}^{\&prime;}X}+\mathrm{\&mu;n}\left|E\right|\frac{\&PartialD;\mathrm{\&Delta;n}}{\&PartialD;X}-\mathrm{R\&Delta;n}$ Wherein $R={<}_{R_A-X_A<X<X_D.X_D<X<X_A}^{R_D-X_D<X<X_D}$

R=＜R wherein _D-X _D＜X＜X _D

R _A－X _A＜X＜－X _D，X _D＜X＜X _A

D _nBe electronics coefficient of diffusion in material, μ n is a mobility.Separating of this equation shows, constantly spreads for the electronics in the body layer to receptive layers, and it is trapezoidal to form concentration, and simultaneously, electron concentration distribution maximum edge-directions X is done drift motion, and drift velocity is μ n|E|.If drift velocity is very big, make the very fast process of electronics give the body layer, then the compounding machine of electronics can be with minimizing in giving the body layer, suitably select extra electric field intensity, can reduce electronics compound in giving the body layer fully, thereby increase the ratio that electronics is captured by acceptor, so that greater than the acceptor compositely proportional R in the single layer structure _A/ R _A+ R _DSimultaneously, if give bulk layer thickness much smaller than electron diffusion length, and receptive layers thickness is greater than electron diffusion length, and then electronics mainly is distributed in the receptive layers, has only a little electrons just to be captured for the body layer again.Therefore, appropriate design sandwich construction and suitably select extra electric field intensity can make to write efficient and be higher than single layer structure.

Provide embodiments of the invention below.

Fig. 1 is structural parameters figure;

Fig. 2 is a synoptic diagram of the present invention.

(1) is electro-conductive glass among the figure; (2) be the electron accepter layer; (3) be the electron donor layer; (4) be the electron accepter layer; (5) be transparency electrode.

Present embodiment adopts Sm ³⁺And MgS, Eu ²⁺System is an example, at first makes MgS with the ordinary sinter method, Sm ³⁺MgS, Eu ²⁺Raw material.Use conventional evaporation coating method, utilize MgS, Sm ³⁺And MgS, Eu ²⁺Be two evaporation sources, on electro-conductive glass, alternately be coated with MgS, Sm ³⁺Electron accepter layer and MgS, Eu ²⁺The electron donor layer is coated with 20 layers, electron donor layer 100 , and electron accepter layer 1000 plate the layer of transparent electrode at last, and this electrode and electro-conductive glass form two electrodes, are used for extra electric field.

After material is made, add the 20V DC voltage by electrode, form electric field in multilayer film, use blue green glow then, a bit write such as 488nm rayed multilayer film plane, write energy is 1 μ l.Add reverse voltage (fashionable polarity of voltage is opposite with writing) 20V when reading, with wavelength 1 μ m, energy writes a little for the irradiation of 10nJ infrared light, and surveying optical stimulated luminescence intensity with general spectrometer simultaneously is 1nJ.Place after 30 days, similarity condition is read, and the measurement luminous intensity is 0.82nJ.After placing 30 days again, similarity condition is read, and the measurement luminous intensity is 0.67nJ.

Claims (1)

1. an optical memory material is characterized in that electron donor center and electron capture center do not exist simultaneously with in one deck, forms electron donor layer and the electron trapping layer alternately arranged.

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