We have developed a new light emitting device named ZOGAN LED. It is composed with the p-layer comprising p-ZnO and p-GaN. ZOGAN LED and GaN LED are dramatically different in device performance. For example, it is well known for GaN LED that the EQE of GaN LED becomes worse, as either the device size is getting smaller, or the injection current is larger. However, unlike GaN LED, ZOGAN LED shows no EQE droop with current increase or size decrease, while keeping its EQE level exceptionally high. No EQE droop and no size-dependent EQE decrease are unique features of ZOGAN LED, which is never ever reported before. The non-radiative leakage current is almost negligible and not increased as the chip size decreases even below 10um for ZOGAN microLED. For these unique properties, ZOGAN microLED is critical to accomplish the high-efficient microLED displays with >5,000PPI resolution.
In this presentation, we will report the features of ZOGAN microLED, based on experimental results of electrical/optical measurements. After brief discussion and review on physical properties of ZOGAN LEDs, ZOGAN microLEDs in different chip sizes (20, 10, and 5 microns in diameter) will be demonstrated.
Micro/Nano LED is one of hot topics for the next generation of display beyond OLED. GaN-based and Phosphide-based LEDs show terribly low emission efficiencies as the chip size gets smaller like <10. Therefore, current LED technology can’t provide efficient micro/nano LEDs suitable for VR/AR/MR display applications.
We will introduce a revolutionary light emitting device, called Hybrid LED, in the presentation. Hybrid LED is composed of ZnO-based Oxide semiconductors and GaN-based Nitride semiconductors. Hybrid LED is a breakthrough for micro-LED display because its emission efficiency is constantly good enough for 5,000+ PPI display without affected by chip size unlike conventional Nitride-based and Phosphide-based LEDs.
After brief discussion and review on Physical properties of Hybrid LEDs, commercial Hybrid LEDs in different colors (from blue to red) and chip sizes (a few to hundred microns) will be demonstrated to show how outstanding Hybrid LEDs are, compared with typical commercial GaN LEDs.
Photoconductors based on wide band gap semiconductors are potential devices for UV light detection due to internal
photoelectrical gain and fabrication simplicity. Photoresponses of photoconductors based on GaN and ZnO show high
values in UV range under large biases and relatively low values in visible range. Although photoresponse of ZnO
photoconductors is similar to that of GaN-based photoconductors, mechanisms of photoconductance between two
materials are very different. This difference can be found in optical power dependence of photocurrent and I-V
characteristics, and has an impact on device design. In this paper we report experimental studies of photoresponse for
newly developed ZnO photoconductors. The ZnO film was grown on a 6H-SiC substrate by hybrid beam deposition. The
photoconductor device is formed with interdigitated finger-shaped Ti/Au ohmic contacts on the ZnO film. Electrical
characteristics, spectral photoresponse, and persistence properties were studied for the device under variable biases. We
find that there are at least three mechanisms involved in the device. At low biases and low incident light power, the
photoresponse is mainly due to photocreation. At higher light power and lower biases, the space charge regions are
responsible for the photocurrent. At higher biases, the contribution from surface states is dominant.
Among wide bandgap materials that are sensitive to photons in the ultraviolet (UV) region, ZnO is a promising photonic
material because of its unique optoelectronic properties. Based on the lateral interdigitated back-to-back Schottky
contact structure on ZnO film, metal-semiconductor-metal (MSM) photodetectors have substantially lower parasitic
capacitance compared with vertical p-i-n photodetectors, which leads to a very high speed photodetection. In this paper,
we report optical characteristics of MSM ZnO UV photodetectors for which ZnO films were fabricated by hybrid beam
deposition. An annealing process was used in oxygen ambient. The MSM ZnO photodetector consists of two
interdigitated electrodes both with Ti/Au metals on an n-type ZnO thin film. The electrodes on the photodetector are
finger-shaped. We found that the annealing process decreases contact resistance and photoresponse time. The possible
mechanism of annealing process is the removal of surface defects created in the fabrication process. A sublinear power
dependence of photocurrent reveals the existence of a light induced space charge region inside the ZnO film. The device
displays fast pulse response with a very short rise time and a relatively long relaxation time with applied bias. The
exponential decay tail indicates an RC type time response.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.