Electroluminescence from Metal Oxide Thin Films

ECS J. Solid State Sci. Technol.

2015

The enhancement of white light emission from the amorphous Zr-doped HfO2 film on the p-type silicon wafer with the embedding of a nanocrystalline cadmium selenide layer has been studied through understanding characteristics of the emitted light, leakage current, surface topography, driving methods and time. All changes of the emission characteristics can be explained with the formation and thermal excitation of the conductive paths. The deterioration of the light emission process over a long period of 5,664 hours has also been investigated and discussed. There are many potential applications of this kind of light emitting device.

Section: Methodsmentioning

confidence: 99%

Light Emission Enhancement by Embedding Nanocrystalline Cadmium Selenide in Amorphous ZrHfO High-k Dielectric Thin Film Deposited on Silicon Wafer

Lin

ECS J. Solid State Sci. Technol.

2015

“…[9][10][11][12][13][14][15][16] It is made from a MOS capacitor composed of an amorphous high-k dielectric thin film, such as Zr-doped HfO 2 (ZrHfO), HfO x , or WO x , on a p-type Si wafer.…”

Section: -3mentioning

confidence: 99%

Post Deposition Annealing Atmosphere Effect on Performance of Solid State Incandescent Light Emitting Device

Zhang

ECS J. Solid State Sci. Technol.

2017

Electrical and optical properties of solid state incandescent light emitting devices made from MOS capacitors of the same Zr-doped HfO 2 high-k film but two different post deposition annealing atmospheres have been investigated. Compared with the N 2 annealed sample, the O 2 annealed capacitor has a thicker and more SiO x -rich interface layer, lower defect densities, a larger dielectric breakdown strength, and a lower leakage current. Light emitted from the solid-state incandescent light emitting device made from the O 2 annealed capacitor has a high intensity and slightly more blue component than that made from the N 2 annealed capacitor due to the higher temperature of the conductive path. The former contains more Si and O elements in conductive paths than the latter does, which can be used to explain the difference in their electrical and optical characteristics. The post deposition atmosphere affected the original high-k stack's material and physical properties, which influences the formation and material composition of conductive paths and eventually the light emission characteristics. If incandescent and fluorescent light lamps are replaced with solidstate light emitting devices (LEDs), the energy consumption from lighting in the United States can be saved by about 38%.1 LEDs are usually made of direct-bandgap semiconductor materials prepared in the p-n junction or quantum well (QW) structure.2,3 They require the growth of high quality compound semiconductor epitaxy layers on single crystal substrates. The process is expensive and tedious. 1-3The light emission principle is the electron-hole or exciton-exciton recombination. The energy of the emitted light is equivalent to that of the bandgap energy of the semiconductor material.1-3 Therefore, the broad-band light cannot be emitted from a single LED. The white light can be generated using 3 different kinds of LEDs, i.e., red, green, and blue light emitting, or a blue LED in combination with a phosphor layer. 4,5 CdSe/ZnS core-shell nanocrystals have been used to convert the blue/UV light into the green/red light, which is also a method of generating the white light. 6,7 However, the size of the nanocrystal has to be tightly controlled to emit a specific color, which is difficult to achieve. 7 The semiconductor based LED is often subject to the "droop" failure mechanism that shortens the lifetime. 8 It is desirable to have a LED that emits the broad band white light from a single device and can be fabricated with the IC-compatible process with a long lifetime. Recently, Kuo's group reported a new type of solid-state incandescent LED (SSI-LED) that emitted the warm white light similar to that of the incandescent bulb.9-16 The light emitting principle of the SSI-LED is the thermal excitation of the nano-sized conductive path from the passage of a current. [9][10][11][12][13][14][15][16] It is made from a MOS capacitor composed of an amorphous high-k dielectric thin film, such as Zr-doped HfO 2 (ZrHfO), HfO x , or WO x , on a p-type Si wafer.9-16 These high-k...

“…2,3 Recently, Kuo and Lin reported a type of solid state incandescent LED (SSI-LED) that emitted the warm white light from a single device. [4][5][6][7][8] The broad band light was emitted from the thermal excitation of conductive paths within an amorphous high-k dielectric thin film such as Zr-doped HfO 2 (ZrHfO), HfO x , or WO 3 . 4-8 These conductive paths are formed from the dielectric breakdown process and therefore self-aligned to the transparent gate electrode.…”

mentioning

confidence: 99%

Light emission from conductive paths in nanocrystalline CdSe embedded Zr-doped HfO2 high-k stack

Lin

Applied Physics Letters

2015

Electrical and optical properties of the solid state incandescent light emitting devices made of zirconium doped hafnium oxide high-k films with and without an embedded nanocrystalline CdSe layer on the p-type Si wafer have been studied. The broad band white light was emitted from nano sized conductive paths through the thermal excitation mechanism. Conductive paths formed from the dielectric breakdown have been confirmed from scanning electron microscopic and atomic force microscopic images and the secondary ion mass spectrometric elemental profiles. Si was diffused from the wafer to the device surface through the conductive path during the high temperature light emission process. There are many potential applications of this type of device.