High-Purity Ultraviolet Electroluminescence fromn-ZnO Nanowires/p⁺-Si Heterostructure LEDs withi-MgO Film as Carrier Control Layer

Abstract

Pure ultraviolet (UV) light emitting diodes (LEDs) using n-ZnO nanowires as an active layer were fabricated with an insulating MgO dielectric layer as a carrier control layer, where all depositions were continuously performed by metalorganic chemical vapor deposition. The current-voltage curve of the LEDs showed obvious rectifying characteristics, with a threshold voltage of about 7 V in the sample with 4 nm i-MgO. Under the forward bias of the samples with proper MgO thickness, a sharp UV electroluminescence, located at around 380 nm, was emitted from the active ZnO nanowires, while weak visible emission of around 450-700 nm were observed. The pure UV emission from the ZnO nanowires in the n-ZnO/i-MgO/p + -Si heterostructures was attributed to the electron accumulation in the ZnO by asymmetric band offset and preemptive hole tunneling from Si to ZnO by i-MgO.

Wavelength-tunable infrared light emitting diode based on ordered ZnO nanowire/Si1–x Ge x alloy heterojunction

“…The EL curves of all the devices have the same general features, with the peak extending from 450 nm to beyond 900 nm and being centered at about 700 nm. This visible EL phenomenon is believed to be due to the defects and surface states of ZnO, in accordance with visible PL emission [18,19,22,24].…”

“…ZnO/Si LED nanodevices have been studied widely, from single wire LEDs to nanowire or nanorod array LEDs [17][18][19][20][21][22][23][24][25]. However, most studies have focused on the electroluminescence (EL) emission of these devices in the visible range.…”

Structural, optical and electronic properties of Fe doped ZnO thin films

“…large exciton binding energy (60 meV), n-type behavior due to oxygen vacancies, Zn interstitial and antisites [4][5][6]. Group II elements are generally used in modifying the band gap of ZnO [7][8]. Also, transition Metals like Fe, Co and Ni have a technical advantage for optical, magnetic, electrical and electronic properties which is required for fabrication of spintronic and optoelectronic devices [9].…”

Effect of substrate temperature and oxygen partial pressure on structural and optical properties of Mg doped ZnO thin films

“…Several recent studies have examined for fabrication and optical properties of doped ZnO films. Group II elements such as Be, Al, Mg and Cd are extensively used in tailoring the band gap of ZnO [7][8][9][10]. Cd doping was studied by many authors for narrowing the band gap of ZnO and Mg doping in ZnO is explored for widening the band gap [11][12][13].…”