ABSTRACT

High Performance ZnO Spintronic devices (Laser and Resonant Tunneling Diodes) With High Switching Speeds and Frequencies

Zinc Oxide has emerged as a key semiconductor that will have a broad range of applications in Opto-electronic and Spintronic devices. ZnO has a large band gap and has potential applications in Light Emitting Diodes (LED). Room temperature ferromagnetism in ZnO has the promise of building Spintronic devices such as laser and resonant tunneling diodes with high switching speeds and frequencies. Some of the key technical challenges include growth of ZnO with p doping. There has been recent success with Nitrogen doping. Magnolia Optical technologies and its team proposes to develop a reliable p-type doping process using Nitrogen as the dopant in MOCVD grown epitaxial films. MOCVD is a better choice then because it is possible to create hetero-junctions and quantum nano-structures in a reproducible manner. These structures are necessary for optimizing UV laser diode performance by device design to maximize excitonic recombination. The Magnolia plans to evaluate Nitrogen incorporation and subsequent annealing. The MgZnO material system has several advantages over other competing material technologies, the availability of a latticed matched ZnO substrate, which enables defect density reduction, and carrier control of doped MgZnO films. Magnolia anticipates that Blue Laser Diodes are a growth segment in optoelectronics. MgZnO has the potential of being three time brighter then GaN. In addition, once the development of p-type doping is mature, MgZnO devices have the potential to be lower cost then GaN devices. It is anticipated that this material can be processed in a true dual use fabrication facility. The advantages are obvious, military systems will benefit from the economies of scale of commercial uses. ZnO blue light emitters will be used in millions of outside large display screens. Other applications include color scanner (FAX, Color copiers, large TV displays and of course optical Storage. Some of the future applications include DVD optical storage based on blue light. This will be a large application and market for ZnO blue emitter devices. Current Technology results in a spot size of 800 nm, blue light will cut the spot size to equal of less then 450nm. The will have a major impact on data density storage market. At the current time GaN blue lasers are very expensive for this application. For current volume, the unit product cost is in excess of $2000 per unit. This is due to the low yield that is currently obtainable with GaN materials technology. The use of lattice matched substrates using ZnO, we anticipate much higher yields due to lower defect densities and therefore lower unit product costs.