RU2540623C1 - Method of forming high-quality heterostructures of light-emitting diodes - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention can be used to produce high-quality semiconductor light-emitting diodes (LED) based on heterostructures of A³B⁵ compounds. The method includes irradiating a plate with heterostructures with integral electron flux with density of 10¹⁴-10¹⁷ el/cm² and energy of 0.3-10 MeV at a temperature not higher than minus 70°C, followed by rapid thermal annealing at a temperature higher than 600°C with photon flux in the visible spectrum with radiation intensity of 1-10 W/cm and energy higher than the band-gap of the semiconductor layer of the heterojunction the narrowest band-gap.

EFFECT: high injection capacity and external quantum efficiency of heterostructures of light-emitting diodes.

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Description

The invention relates to the field of semiconductor optoelectronics and can be used to create high-quality semiconductor light-emitting diodes (LEDs) and heterostructures of compounds A ³ B ⁵ .

It is known that the properties of the heterojunction injection depends on the perfection of the interface contacting semiconductor materials, usually containing dislocation density N _d <10 ⁹ -10 ¹⁰ cm ^2, a large number of stacking faults _do N> 10 ⁴ cm ² and inversion domains. The degree of perfection of heteroboundaries is usually characterized by the rate of surface recombination [1. Martynov V.N., Koltsov G.I. “Semiconductor optoelectronics” - M .: MISIS Publishing House, 1999, p. 84], the value of which is determined by the correspondence of the lattice parameters, elastic and thermal coefficients of the contacting materials.

There are various ways to improve the external quantum efficiency of LEDs, in particular by applying porous oxide to the surface of heterostructures [2. A method of manufacturing an LED, RF patent No. 2485630 from 08/04/2011], the formation of micro-bulges, grooves, microrelief on the surface of the emitting layer [3. Semiconductor light-emitting device and method for its manufacture, RF patent No. 2436195 from 12.26.2008; 4. A semiconductor element, a method of manufacturing a semiconductor product and a matrix of light emitting diodes obtained using this manufacturing method, RF patent No. 2416135 of 10.25.2007; 5. Light-emitting diode, RF patent No. 2231171 from 04/30/2003], as well as by processing semiconductor and dielectric structures, in particular by irradiation with electron flows, under the conditions of an applied electric field [6. The method of processing diamonds, RF patent No. 2293148 from 07/17/2002], in an electric field at high temperature [7. The method of forming impurity profiles in semiconductor materials, RF patent No. 2197571 from 09/13/2000].

Such methods do not provide the best quality of the interfaces of heterostructures in LEDs and, accordingly, high external quantum efficiency of radiation, since the methods [2. A method of manufacturing an LED, RF patent No. 2485630 from 08/04/2011; 3. Semiconductor light-emitting device and method for its manufacture, RF patent No. 2436195 dated 12/26/2008; 4. A semiconductor element, a method of manufacturing a semiconductor product and a matrix of light emitting diodes obtained using this manufacturing method, RF patent No. 2416135 of 10.25.2007; 5. Light emitting diode, RF patent No. 2231171 from 04/30/2003; 6. The method of processing diamonds, RF patent No. 2293148 of 07.17.2002] little effect on the interface between the semiconductor layers of the LED.

This disadvantage is partially eliminated in the method of processing plates presented in the patent, taken as a prototype, in which [7. The method of forming impurity profiles in semiconductor materials, RF patent No. 2197571 from 09/13/2000] uses an electric field of E = 10-100 V / cm and a high temperature T = 600-850 ° C during the irradiation of semiconductor devices with an electron flux of F = 10 ¹⁴ -10 ¹⁶ el. / cm ² with an energy E _e = 0.3-10 MeV, which can effectively control the distribution of impurities in the semiconductor. However, this method also does not provide the minimum value of the density of surface states N _cc <10 ¹¹ cm ^-1 , the dislocation density N _d <10 ⁹ -10 ¹⁰ cm ² and stacking faults N _du <10 ⁴ cm ² .

The technical result of this invention is to increase the injection ability and external quantum efficiency of LED heterostructures.

The specified technical result is achieved by the fact that in the proposed method for the formation of high-quality heterostructures of LEDs, irradiation of plates with heterostructures of LEDs is performed by an electron flux F = 10 ¹⁴ -10 ¹⁷ el./cm ² at a low temperature not exceeding minus 70 ° С, then a fast thermal annealing is carried out the photon flux of the visible spectrum with a power exceeding 1 W / cm ² with an energy exceeding the band gap of the narrowest gap semiconductor layer of the heterojunction.

It should be noted that a positive effect, but much smaller (by an order of magnitude), is observed during “ordinary” thermal annealing in a diffusion furnace at a temperature of 450-650 ° C.

The proposed method is implemented, for example, as follows (drawing 1). Aluminum box - 1 with thin walls (0.3 mm), containing a quartz boat - 2 with plates - 3 (no more than five to six pieces) with Ga _0.67 Al _0.33 As heterostructures, cooled with nitrogen coming from the Dewar vessel to a temperature below minus 70 ° С, they are placed in a stream of electron radiation with a power of 10 ¹⁴ el./cm ² sec with an electron energy of 0.3-10 MeV and irradiated for two hours. Then the plates are illuminated with a halogen tungsten source, providing a wide range of visible and infrared ranges with a radiation intensity of 1-10 W / cm ² . The process of forming the structure is 1-2 minutes.

The physical essence of the process is the formation by electron radiation with an energy exceeding a certain threshold value, usually more than 150 keV, in the semiconductor material of point defects of the type vacancy - interstitial. In this case, irradiation is carried out at the lowest possible temperature (less than minus 70 ° C) so that these defects do not move and do not recombine. Subsequent rapid and intense heating (more than 600 ° C), the interface is rearranged between semiconductors due to radiation-stimulated diffusion of atoms by point defects into the lowest (favorable) energy state.

Experimental studies by the RSGU method and CV characteristics showed that the density of surface states in Ga type heterostructures _0.67 Al _0.33 As decreases to the level N _cc <10 ^-9 -10 ^-10 cm- ¹ , the dislocation density N _d <10 ⁸ -10 ⁹ cm ² and stacking faults N _DN <10 ² cm ² , which leads to an increase in the external quantum efficiency and injection coefficient by 20-30%.

Claims (1)

A method of forming high-quality heterostructures of light-emitting diodes, comprising the operation of irradiating plates with heterostructures with an integrated electron flux of value Ф = 10^fourteen-10¹⁷ e / cm² with energy E_e= 0.3-10 MeV, characterized in that the irradiation of plates with heterostructures is carried out at a low temperature not exceeding minus 70 ° C, then a fast thermal annealing is carried out at a temperature of more than 600 ° C with a photon flux of the visible spectrum with an emission intensity of 1-10 W / cm with an energy exceeding the band gap of the most narrow-gap semiconductor layer of the heterojunction.

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