Study For Intergrated LED Micro Arrays Device Based On MEMS Technology

Light emitting diode(LED) is widely applied in illumination, self-emissive display, aviation, medical treatment, biological neuron network and communication network, owing to the advantages that high brightness, low power dissipation, rapid response speed and high reliability and so on. Recently, integrated micro-LED array device was studied by many groups due to the commercial and technological requirement for microdisplay, micro optical communication and high resolution LED display device.In this thesis, the integrated micro-LED device based on common AlGaInP epitaxial wafer was studied. The device with high resolution and integrated density was fabricated by MEMS and semiconductor technology. This work includes four parts:1. The influence of divided pixels array on radiative intensity and illumination on receiver was analyzed when AlGaInP-LED chip was used for illumination; When a 300?m×300?m chip was divided into 3×3 small pixels with size of 80?m×80?m and adjacent spacing of 20?m, the total saturated output power was 5.19 times and the maximum inject current increased nearly 7 times. The results indicated that it could obtain larger inject current and saturated light output power to divide LED chip into small pixels. Besides, when multiple divided chips were used for illumination, the uniformity of illumination on receiver reached its peaks as the distance of LED chip equaled to the maximum flat condition dmax. and the area with uniform illumination increased along with the number of LED chips increasing. When the target plane was illumined by nine LED chips with size of 300?m×300?m, although the uniformity was changeless, the illumination was three times the non-divided chip arrays as the chip was divided into nine pixels with size of 80?m×80?m and distance of dmax.2. For the nonuniform problem of internal current density distribution in micro AlGaInP-LED device, the influences of anode electrodes on pixel internal current density distribution was analyzed by Silvaco software. With the same luminous area, the pixel internal current density distribution in pixel with four types of anode electrode structure were contrasted and analyzed. The results indicated that current density distribution was more uniform, the saturated light output power of single pixel(about 50W/cm2) was higher, and the temperature in pixel was lower for five-fingers comparing with other types.3. The procedures for fabricating micro Al GaInP-LED arrays device and measurement were designed and the device was manufactured subsquently. Firstly, the AlGaInP chip was grooved with aspect-ratio of 2:1 to achieve high density isolated pixels. Next, polymide was filled in grooves or polymide film was covered on grooves as support of electrode bridges which connected pixels in the same row. The anode electrode arrays were fabricated by etching or peeling technology. Finally, cathode electrodes were fabricated after substrate was etched by chemical or mechanical technology until all pixels became isolated each other. Moreover, optical and electrical characteristics of the device were measured. With substrate thickness of 150?m, the turn-on voltage was ~1.7V and single pixel light output power was 326?W at inject current of 10 mA.4. For the requirement of wide distance between pixels in flexible LED array device and other special application field, the methods that multi-masking chemical etching and septal etching were proposed to achieve wide distance in flat LED arrays device. The reliability of the methods were tested by experiment and both achieved wide pixel distance which was suitable for flexible LED array device.