A Study On Al Component Of GaN-based UV-LED MQW Barrier

Since their unique physical and chemical characteristics,the III-nitride semiconductors have attracted more and more attention from scientific researchers.Especially because of their direct band gap,high-voltage resistance,high electron escape rate,and the ability to withstand extreme temperature,they are widely favored by the photoelectric lighting market.The most representative of these materials is the third-generation semiconductor GaN,which has more photoelectric conversion advantages than the first-generation semiconductor materials Si and Ge and the second-generation semiconductor material GaAs.However,Gan-based blue and green LED light for GaN-based UV LEDs where the epitaxial process and device structure are relatively mature,there are still many unresolved problems,such as the luminous efficiency of UV LEDs and the quality of epitaxial crystals with high Al composition.These problems are he main reasons for restricting UV LEDs to replace traditional UV light sources and open a huge consumer market.Therefore,this paper explores the phenomenon of low quantum carrier recombination efficiency of GaN-based LED devices.It is planned to test the performance of experimental samples by means of PL,EL,HRXRD,AFM,and Raman tests.The above-mentioned characterization methods are used to calculate the stress type,dislocation density and band width of the optoelectronic device.Our experimental data will be combined with the band theory and stress theory to explain the cause of the change in carrier recombination efficiency.Based on the above ideas,the main experimental contents of this paper are as follows:The first group of experiments was used to study the relationship between the hole injection quantum well efficiency in LED devices and the Al component of the quantum well barrier layer.The Al component of the quantum well barrier layer was successively divided into three groups.After the above test methods,the experimental group of the quantum well layer Al group,which was divided into 8%,had more balanced data in all aspects,with smoother surface,less internal stress and the lowest dislocation density.In particular,in terms of luminous efficiency and brightness,LOP could reach 69.5mw.The radiation recombination efficiency is highest in the quantum well of this device,because when the Al component in the quantum well barrier layer of LED devices is moderate,it is closer to the Al component in the supergrid work of P layer and the superlattice in front of the quantum well,and the Al element at this concentration does not exceed the limit of lattice mismatch.Therefore,the stress caused by lattice mismatch can be reduced,and the crystal quality of LED devices is better.However,since the wavelength of the first set of experiments was above 370 nm,a second set of experiments was started to reduce the wavelength.The second group of experiments is to stabilize the luminescence wavelength below 370 nm.On the premise of the basic process,the barrier Al group is divided into 8% of the first group selected in the experiment.Considering the lattice mismatch between the potential well and the barrier,the Al component in the potential well is divided into three groups.Finally,after the EL test,under the premise of ensuring the optical output power,the sample with a stable luminous wavelength of about 365 nm and an Al content of 3.5% was selected.However,as the working voltage of this sample is over 4V,it is necessary to reduce the equivalent resistance.The purpose of the third group of experiments is to reduce the forward voltage,so in the basic process,the operating voltage is changed by adjusting the thickness of the potential well,and the thickness of the potential well is set in three groups in turn.Finally,through the EL test,the samples with operating voltage of less than 4V were selected.However,the optimal parameters of the three groups of experiments need to be integrated into the stability experiment.The fourth group of experiments is a comprehensive stability experiment.The optimal parameters in the first three experiments are epitaxial growth.The overall stability is analyzed through six batches of epitaxial growth and the EL test.Through the experiments,the hole injection concentration and electron leakage of the quantum well structure have been improved to a certain extent,so that the luminous efficiency and EQE of the LED device have been effectively improved,and the problem of the decline of the quantum effect of the LED has been suppressed.It also points a certain direction in solving the problem of luminous efficiency of UV LED.