Deep ultraviolet light emitting diode chip with high luminous efficiency and preparation method thereof

Abstract

The invention relates to the technical field of a semiconductor device, in particular to an inverted deep ultraviolet light emitting diode chip with high luminous efficiency and a preparation method of the chip. In the inverted deep ultraviolet light emitting diode chip with high luminous efficiency, provided by the invention, a Ni / Al material with high ultraviolet reflectivity is selected and used as a p-type electrode material, the ohmic contact performance between a metal electrode and p-type GaN can be partially improved, and ultraviolet light also can be reflected to a sapphire surface. According to the preparation method of the inverted deep ultraviolet light emitting diode chip with high luminous efficiency, provided by the invention, a sapphire substrate of an epitaxial wafer is thinned to a specific thickness, an Al thin film with an appropriate thickness is evaporated, and the surface luminous efficiency of the inverted deep ultraviolet light emitting chip is partially improved by coupling of TM-mode ultraviolet light and surface plasmon.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a flip-chip deep ultraviolet light-emitting diode chip with high light extraction efficiency and a method for preparing the chip. Background technique [0002] AlGaN is a direct bandgap semiconductor material with stable physical and chemical properties. By adjusting the aluminum composition in the material, Al x Ga 1-x The band gap of N(0≤x≤1) varies between 3.4eV(GaN)-6.2eV(AlN), based on Al y Ga 1-y N / Al z Ga 1-z The interband transition of the N quantum well material can realize a 200-365 nanometer adjustable all-solid-state ultraviolet light-emitting diode light source. Compared with traditional mercury lamps, the new AlGaN-based ultraviolet light-emitting diodes have many advantages: 1. The structure of ultraviolet light-emitting diodes is simple, does not contain fragile glass shells, is portable and impact-resistant, and the working voltage is only a fe...

AI Technical Summary

Problems solved by technology

[0003] However, the efficiency of deep ultraviolet light-emitting diodes below 315 nanometers is relatively low, and the external quantum efficiency is only less than 15%. AlGaN materials have a high dislocation density (>10 10 cm -2 ), these dislocations may extend to the active region of the quantum well, thereby forming a non-radiative recombination center, and finally the internal quantum efficiency of the LED device is reduced

Second, the doping of AlGaN materials with high Al composition is difficult

Since there is no inversion symmetry, the AlGaN material with wurtzite structure has strong spontaneous polarization and piezoelectric polarization along the [0001] growth direction, and a polarization of MV / cm level can be formed in the quantum well region. The electric field causes the wave functions of electrons and holes to be separated in space, which greatly reduces the radiative recombination rate and reduces the internal quantum efficiency of light-emitting diode devices.

Fourth, it is difficult to emit light from the surface of c-plane AlGaN-based deep ultraviolet light-emitting diodes

[0004] For the above-mentioned problems caused by the crystal field splitting energy band position change and electrode material selection of deep ultraviolet light-emitting diodes, there is still no corresponding system solution in the world to enhance surface light emission. The p-type electrode material generally used is also generally Ti / Al / Ti / Au etc.

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