RU120287U1 - Light emitting element - Google Patents

Abstract

A light-emitting element containing p- and n-type silicon layers, between which, in the region of its pn-junction, an active semiconductor layer is enclosed, including β-FeSi2 nanocrystallites embedded in single-crystal undoped silicon, characterized in that the active layer is saturated with β-FeSi2 nanocrystallites with sizes from 20 to 40 nm.

Description

The invention relates to light emitting elements with a wavelength from the near infrared region of the spectrum.

A silicon-based light-emitting device is known, including a pn junction near which an emitting zone is formed, doped with rare earth impurities, based on the same semiconductor material as the active layers of n- and p-type conductivity (see US patent No. 6828598, IPC H01S 3/16, H01S 5/30, H01S 5/32, 2004). Depending on the level of doping of the active layers, the mechanism of tunneling, avalanche, or mixed breakdowns is implemented in the devices. The main limiting factor in the practical use of devices created in a known manner, despite their simplicity and integrability in microelectronic circuits, is their low emissivity and, therefore, low output power of the device.

Also known is a light emitting element containing p- and n-type silicon layers, between which an active layer of a semiconductor comprising β-FeSi ₂ grains embedded in single-crystal unalloyed silicon is enclosed in the region of its pn junction (see US patent No. 6368889, IPC H01L 33/26; H01L 21/00; H01L 33/00, 2002)

The disadvantage of this technical solution is the significant (about 100 nm) grain size of the iron disilicide, which does not allow for a high efficiency of the light-emitting element due to the insufficiently good integration of the grains into the silicon matrix and the relaxed internal structure.

The problem to which the claimed utility model is directed is expressed in increasing the efficiency of light output of the light-emitting element.

EFFECT: increased efficiency of light emission of a light-emitting element due to the possibility of decreasing crystallite sizes of β-FeSi ₂ semiconductor iron disilicide (up to 20-40 nm) and ensuring their high density (number of crystallites per unit volume of a silicon matrix) and due to this elastic incorporation into silicon matrix and significant tension of the internal structure of crystallites.

The solution of this problem is provided by the fact that a light-emitting element containing p-type and n-type silicon layers, between which an active layer of a semiconductor comprising β-FeSi ₂ nanocrystallites embedded in single-crystal unalloyed silicon is enclosed in the region of its pn junction, is characterized in that the active layer is saturated with β-FeSi ₂ nanocrystallites with sizes from 20 to 40 nm.

A comparative analysis of the features of the claimed and well-known technical solutions indicates its compliance with the criterion of "novelty."

The features of the distinctive part of the utility model formula provide a solution to the technical problem posed, namely, increasing the light emission efficiency of the light-emitting element.

The utility model is illustrated by drawings, in which Fig. 1 schematically shows a general view of a light-emitting element, Fig. 2 shows an image of a silicon surface obtained by scanning atomic force microscopy, on which nanoislands of iron disilicide β-FeSi _{2 are formed} , which will subsequently be are aggregated into nanocrystallites of iron disilicide β-FeSi ₂ with sizes of 20-40 nm.

The figures show the components of the light emitting element:

1 - a substrate made of silicon of the first type of conductivity, for example, n-type;

2 - a layer of undoped silicon;

3 - nanocrystallites of iron disilicide (β-FeSi ₂ ),

4 - layer of single-crystal unalloyed silicon

5 - silicon layer of the second type of conductivity, for example p-type;

6 - positive electrode

7- negative electrode.

8 - nanoislands of iron disilicide β-FeSi ₂ .

On the upper end surface of the substrate 1 with a slice along the crystalline plane (100) or (111), an undoped silicon layer 2 is placed on which an active layer of nanocrystallites 3 placed overgrown with an undoped silicon layer 4 is placed. Above the active layer with nanocrystallites 3 there is a silicon layer 5 of the second type of conductivity. A positive electrode 6 is placed on the upper end surface of the light-emitting element, and a negative electrode 7 is located on the bottom.

The formation on the silicon surface of nanoislands of iron disilicide (at an intermediate stage) is confirmed by the image of the sample obtained by scanning atomic force microscopy (see figure 2). This sample was obtained by precipitation of 0.2 nm of iron at a speed of 4 × 10 ^-3 nm / s. Most of the surface is occupied by small islands with lateral dimensions of 24 nm, a height of 4 nm and a concentration of 4.7 × 10 ¹⁰ cm ^-2 . The islands have a rounded shape and are located separately from each other or are arranged in chains up to 7 islands long. In addition, on the surface there is a small number of large islands (concentration 7 × 10 ⁸ cm ^-2 ), the sizes of which are approximately 2 times larger than the sizes of small islands: height - 9 nm, and lateral sizes - 39 nm.

The preparation of the light-emitting element (including the active layer located in the pn junction zone) can be formed using the following technology:

Example. An epitaxial silicon layer is formed on the substrate by deposition of undoped silicon when the substrate is heated to 700-750 ° C, a thickness of 100 to 200 nm with a deposition rate of 5 × 10 ^-2 - 3.3 × 10 ^-1 nm / s, which ensures the formation of a buffer a layer of unalloyed silicon 2. Then, the substrate 1 (with a layer of unalloyed silicon 2 deposited on it) is cooled in a known manner to room temperature. Further, while maintaining the temperature of the substrate at this level, an iron layer 0.2-0.8 nm thick is deposited on the surface of the unalloyed silicon layer with a deposition rate of 1.7 × 10 ^-3 -1.7 × 10 ^-2 nm / s. Next, the iron layer is aggregated into β-FeSi ₂ nanoislands, for which the substrate is annealed at a temperature of 630 ° C for 20 minutes. Moreover, on the surface of the substrate 1 with the formed buffer layer 2 during the interaction of silicon atoms with iron atoms, nanoislands 8 of iron disilicide β-FeSi _{2 are formed} (see Fig. 2). Next, aggregation of the nanoislands 8 of iron β-FeSi ₂ iron disilicide into 20 β-FeSi ₂ iron disilicide 3 nanocrystallites with sizes of 20-40 nm, elastically integrated into the silicon matrix is carried out, for which the epitaxial layer of undoped silicon 4 is deposited when the substrate is heated to 600-800 ° C, a thickness of 100 to 200 nm at a deposition rate of 5 × 10 ^-2 -3.3 × 10 ^-1 nm / s. In the process of such overgrowth, nanocrystallites are distributed in the bulk of silicon, moving in the direction of the front of epitaxial growth of silicon. After that, a silicon layer of the second type of conductivity 5 is formed, for which purpose silicon of the second type of conductivity is deposited with a thickness of 100-200 nm at a deposition rate of 5 × 10 ^-2 -3.3 × 10 ^-1 nm / s and when the substrate is heated to 700-750 ° FROM.

Since silicon of the first type of conductivity (in this case, for example, n-type) is chosen as the substrate, the epitaxial layer of silicon of the second type of conductivity must be represented by p-type silicon, in order to enable the formation of a pn-junction region (when using a substrate of silicon p-type, the epitaxial layer of silicon should be n-type, ie the phrases "first type" and "second type" only speak about the need to use silicon of different types of conductivity).

Upon completion of this process, on the external surfaces of silicon (respectively, the free surface of the epitaxial layer of silicon of the second type of conductivity and the free surface of the substrate), positive 6 and negative 7 electrodes are formed in a known manner, completing the process of formation of the light-emitting element.

Claims (1)

A light-emitting element containing p- and n-type silicon layers between which an active layer of a semiconductor comprising β-FeSi ₂ nanocrystallites embedded in single-crystal unalloyed silicon, characterized in that the active layer is saturated with β- nanocrystallites, is enclosed in the region of its pn junction FeSi ₂ with sizes from 20 to 40 nm.