The Preparation Technology Of AlGaInP RLED On A Metallic Substrate And Study On Characteristics

Light-emitting diode?LED?as a new generation of lighting source,green environmental protection,small volume,long service life,low power consumption and a series of excellent properties,is replacing the traditional lighting light source gradually.With the continuous development of LED epitaxy chip and manufacturing technology,the high power LED,high brightness and low cost has become a focus in the study of the race.Quaternary(Al_xGa_1-x)_0.5In_0.5P alloy semiconductors are direct band gap materials when Al components is less than 0.53,and forbidden band width is about 1.9².3 ev.Now,(Al_xGa_1-x)_0.5In_0.5P are widely used in the preparation of red,yellow,and green light emitting diode which have great application in full-color displays,traffic signal lighting automotive lighting and large area display.The lattice-matched AlGa InP with multiple quantum wells?MQWs?structure grown on a GaAs substrate has become the excellent luminescent material to prepare the red light LED devices,its quantum efficiency can reach above 90%.However,the achievement in high luminous efficiency and excellent heat dissipation,life still has much room for improvement.The main reason is that the serious light absorption by the GaAs substrate,reduce the luminous efficiency of LED..At the same time,the working stability and life of the high power light-emitting diodes were impacted badly due to the poorer thermal conductivity of the GaAs substrate.Combining with the substrate transfer technology,The problem of absorption and heat dissipation of GaAs substrate can be well solved with the metal-substrate,which have good thermal-conductivity,electrical-conductivity,high-ductility and reflectivity.Now it is the ideal substrate material of the high-power AlGa InP light-emitting diodes.The preparation of high-power AlGaInP red light-emitting diodes.At present,wafer bonding technology are the main preparation technology of metal substrate red light LED.But it has certain disadvantages:1,The need to high temperature and high pressure conditions,easy to introduce damage stress,reduce the device performance,and even make the epitaxial wafer warp caused fracture.2,High cleanliness and smoothness requirements of the epitaxial bonding surface,increasesing the difficulty of the preparation technology.3,The particles on the epitaxial chips caused extensive damage,reducing the rate of finished product,at present,high-power LED to yield is only about 50%prepared with the wafer bonding technique.In order to solve the wafer bonding technology problems in preparation of metal substrate high-power red LED,we developed the LED technology is suitable for industrialized production of superpower,adopt new technology of metal based on the technology of electroplating copper substrate,greatly improve the product performance and chip yield?90%?.Its main advantages are:1.The eliminated for the bonding temperature,bonding pressure,flatness,strict requirements of cleanliness,effectively improve the performance and coefficient of the product.2.The plating cost and simple process.3.According to the need to adjust the plating parameters:current value,time,plating solution,temperature,PH value,to adjust the stress state of the device,so as to better control device quality.4.High conductivity and thermal conductivity of the copper,excellent to solve the thermal issue of high power LED devices,and can effectively improve the LED photoelectric performance.5.The metal copper on red long wavelength light all have high reflection coefficient,reflectivity can reach more than 90%,and without being limited by the incidence Angle,greatly improve the light extraction efficiency of the device.6.good compatibility,applies not only to the red LEDs,also as the yellow green LEDs and so on.With GaAs substrate stripping and acidic copper plating technology,can effectively improve the external quantum efficiency of AlGaInP red light-emitting diodes as well as solve the heat dissipation problem.The main contents are:1.The technical scheme of AlGa InP LED with Electroplating copper substrate:Combining theory and practice,the structure of AlGaInP RLED device are determined,such as choosing the appropriate chip size,space between and ohmic contact electrode type,shape,etc.We finally adopt plating copper substrate transfer technique which was used to prepare high-power AlGaInP RLED,which considering the device brightness,photosynthetic efficiency as well as device process conditions.2.Performance testing about AlGaInP RLED with Electroplating copper substrate:Studying the photovoltaic device performance and stability of AlGaInP RLED.The paper test the photoluminescence and electrically spectrum,I-V characteristics,in addition,the variation of peak wavelength,a half-high width,luminous flux,luminous efficiency relative to the electric current were measured.The results show that at equivalent current injection,the metal-base AlGa InP RLED forward voltage decreased than the conventional RLED;The luminous flux increased by 73.5%and 142%comparing with common AGa InP RLED when 20 mA and 350 mA current injection.Beyond that,the saturated Luminous flux current value and the thermal stability were improved.The main reason is the good thermal conductivity and good electrical conductivity of electroplating copper substrate,making for heat dissipation.meanwhile the electrode can be served as metal mirror,which improved the luminous efficiency and photoelectric performance stability of AlGaInP RLED.