Ultraviolet (UV) lasers have a variety of applications in many fields like machining, labeling, measuring, and guiding, etc. Wide bandgap semiconductors are one of the most promising candidates for efficient and robust UV lasers. ZnO has a wide bandgap (3.37 eV) and large exciton binding energy (60 meV), which promises that lasers can be realized in ZnO in relatively simple ways. There have been many reports on optically pumped lasers from ZnO nanowires, films, and even powders in recent years, which confirm that UV lasers can be realized. Nevertheless, to realize the future applications of UV lasers, electrically pumped lasers are greatly wanted. Efficient electrically pumped lasers are usually realized inp-njunctions. However, ZnO is intrinsically ann-type semiconductor, it is still a huge challenge to dope the intrinsicn-type ZnO intop-type conduction. Actually many efforts have been devoted to thep-type doping of ZnO, although some progresses have been achieved, reproducible and reliablep-type ZnO is still rarely reported to date. It is accepted that thep-type doping of ZnO and other wide bandgap semiconductors has two major obstacles, one is the relatively large activation energy of acceptors, and the other is the relatively strong compensation. The large activation energy will impede the release of holes from the doped acceptors, while the strong compensation means that the doped acceptors will usually be electrically compensated by the residual donors or generated donors during the doping process. The aforementioned large activation energy and strong compensation hinder drastically the realization ofp-type conductivity in wide bandgap semiconductors. Actuallyp-type doping of ZnO has been one of the most challenging issues in recent years.

In a paper published in Scientific Reports (Sci. Rep. 5, 13641 (2015)), researchers from Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Hong Kong Polytechnic University and Zhengzhou University, demonstrated an electrostatic doping method, in which a negative bias was applied onto ZnO/MgO heterstructures, electrons in the ZnO layer will be depleted at the interface of the heterostructures by the bias, and holes will dominate the carrier transportation along the interface, while the other region is still electron dominated. In this way, quasip-njunctions have been formed, and by applying forward bias to the quasip-njunctions, UV lasing has been observed. The results reported in this paper may provide an alternative route to efficient optoelectronic devices by circumventing the two major obstacles of large activation energy and strong compensation during thep-type doping of wide bandgap semiconductors, thus may promise high-performance ultraviolet optoelectronic devices.

Publication

Ultraviolet Lasers Realized via Electrostatic Doping Method.
Liu XY, Shan CX, Zhu H, Li BH, Jiang MM, Yu SF, Shen DZ
Sci Rep. 2015 Sep 1

Read offline:

Related Articles:

	Sustainable ZnSnO3 nanowires produced by a low-cost solution…Oxide materials, and more specifically, multicomponent oxide materials, have been widely explored in thin-film technology, being the indium-based materials very common. For example, conductive indium-tin oxide (ITO) or semiconductive indium-gallium-zinc…
	Site-specific antibody labeling with novel photocrosslinking…Our research presents a novel, site-specific approach to labeling antibodies with molecules for various applications, improving upon traditional methods of antibody conjugation. The method is widely compatible and modular, enabling…
	Bioinspiration on the lotus leaf surface to develop…The production and application of synthetic materials in food packaging has grown quickly over the past few decades, resulting in serious environmental concerns due to the resistance to degradation of…
	DFT for designing efficient supercapacitor electrode…Josef MacDouall once said “Chemistry is a game that electrons play”. If one were able to know the roles, they could control the game and uncover the mysteries of materials,…
	Flexible solid-state random lasers emitting radiation in the…The internet of things opened new possibilities relative to the integration of wearable electronics in textile-based devices, allowing the development of new technologies in energy storage and energy harvesting area,…
	Layer-dependent fast electron transfer at the…The photo-induced effective interfacial charge separation in Zn phthalocyanine/few-layer graphene heterojunctions has been a promising observation for fabrication of efficient energy-conversion devices. Few-layer graphene are two-dimensional (2D) systems composed of…