High-brightness inverted InGaN-GaN multiple-quantum-well light-emitting diodes without a transparent conductive layer

Unlike the conventional layer structure of an InGaN-GaN multiple-quantum-well light-emitting diode (LED), an LED with reversed p-type and n-type layer sequence, and an n+/p+ tunnel junction has been investigated. When operated at 20 mA, the output power of the inverted LED is almost twice that of the conventional LED. Since the structures of these two LEDs are alike when analyzed by X-ray diffraction, the improvement in the light intensity could be attributed to the elimination of the absorption/reflection by the transparent conductive layer and/or some quality improvement of p-type GaN in the inverted LED.     

Cournot competition in spatial markets: Some further results

In contrast to most of the literature on a circular market in which firms choose to disperse equally from each other in equilibrium, this research note shows that the equal-distance dispersion in a circular market results from the substitutability of products produced by two single-plant duopoly firms. Meanwhile, agglomeration at one point results from complementarity. In the multi-plant duopoly case, we find - in contrast to Chamorro-Rivas (2000) - that when firms sell complements, the equilibrium locations tend to exhibit both inter-firm agglomeration and intra-firm dispersion. In other words, the location layout in equilibrium exhibits spatial agglomeration (by pairs) finitely at many points.Received: 8 February 2002, Accepted: 28 October 2002, JEL Classification: D43, L13We would like to thank Chien-Fu Chou, De-Xing Guan, Jacques Poot, and three anonymous referees for their valuable comments. Responsibility for any remaining errors rests with the authors.