The Achievement of a Zinc Oxide‐Based Homojunction Diode Using Radio Frequency Magnetron Cosputtering System

Abstract

(Al + N)-codopedp-type zinc oxide (ZnO)/undopedn-type ZnO homojunction structure was deposited onto Si (100) substrate by using radio frequency (rf) magnetron cosputtering system. Transparent indium tin oxide (ITO)-ZnO cosputtered film was employed as the ohmic contact electrode to then-type ZnO film, and the specific contact resistance was optimized to2.9×10-6 Ω cm2after treating by a rapid thermal annealing (RTA) process at 400°C for 5 min under vacuum ambient. The ohmic contact behavior between the metallic Ni/Au andp-ZnO film also was improved to3.5×10-5 Ω cm2after annealing at 300°C for 3 min under nitrogen ambient. The interfacial diffusion of these ohmic contact systems which led to the optimization of the specific contact resistances by the RTA process was investigated by the Auger electron spectroscopy (AES) depth profile measurements. The diode characteristics of the resultingp-ZnO/n-ZnO homojunction structure realized with these ohmic contact electrodes were confirmed by current-voltage (I-V) measurement, which performed a forward turn-on voltage of 1.44 V with a reverse current of1.1×10-5 A at −2 V.

Investigation on the Deposition of an AlN-ZnO/ZnO/AlN-ZnO Double Heterojunction Structure Using Radio Frequency Magnetron Cosputtering Technology

“…Accordingly, ZnO material is expected to be more promising than the current mainstream GaN-based device for short-wavelength optoelectronic applications [1][2][3][4]. Additionally, the growth in technology and temperature necessary to realize a ZnO film with quality c-axis crystallization is much simpler, such as when done by sputtering, pulse laser deposition, and hydrothermal methods, rather than for the epitaxial GaN layer, resulting in potentially low-cost fabrications and processes for ZnO-based devices [5][6][7][8]. Among these deposition methods, sputtering technology is a commercially used method for preparing large-area and cost-efficient polycrystalline ZnO layers on various substrates in applications for optoelectronic devices at a relatively low temperature.…”

Origin of the Electroluminescence from Annealed-ZnO/GaN Heterojunction Light-Emitting Diodes

“…Among these deposition methods, sputtering technology is a widely used technology for preparing quality and large-sized ZnO film on substrates at a relatively low temperature. However, although there has been some progress made using various growth methods and dopant elements to achieve p -ZnO [ 7 , 8 , 9 ], one current problem that impedes the development of ZnO-based homojunction devices is the lack of reliable and reproducible high quality p -type conductivity for ZnO. While p -ZnO is difficult to obtain, p -GaN which has an almost identical in-plane lattice parameter (lattice mismatch ~1.8%) and wurtzite crystal structure to ZnO film, has been employed to realize an n–p heterojunction light emitting diode (LED).…”