Work package 6: Monolithic Integration of RGB LEDs & Integrated RF Electronics for LiFi

Building on the work in the platform our approach is to integrate nitrides micro light emitting diodes (µLEDs) and HEMTs on a single wafer in order to demonstrate and then manufacture monolithic on chip integration of µ LEDs and HEMTs for ultra high resolution ultra high efficient micro displays and ultra fast zero cross talk for Li Fi. We will continuously develop industrial compatible epitaxial overgrowth steps to integrate CS/Si structures with different designs on the same substrate.

Lead

Prof Tao Wang (t.wang@Sheffield.ac.uk)

Overview

Li-Fi exhibits striking advantages compared with current Wi Fi technology in terms of bandwidth, data transmission speed. The major component of Li-Fi is visible LEDs which need to have ultra fast response time and need to be controlled by high frequency electronic components. The most promising approach to achieving high bandwidth and high data transmission rate for Li-Fi to utilise µ LEDs. Furthermore, AR VR micro displays, smart watches and smart phones require µLEDs with an ultra small dimension, high EQE and narrow spectral linewidth On chip epitaxial
Integration of III nitrides µ LEDs and HEMTs on low cost and up scalable silicon substrates for Li-Fi and micro displays is the best way forward,
where the LEDs transmitters can be controlled by GaN based HEMTs uniquely.

We Aim:

  • To develop a disruptive technology for manufacturing monolithic on chip epitaxial integration of CS electronics and optoelectronics.
  • To demonstrate and then manufacture monolithic on chip integration of µLEDs/HEMTs with the highest Max EQE of 20 for micro displays.
  • To demonstrate and then manufacture monolithic on chip integration of µLEDs, HEMTs, Waveguides, Photodetectors for Li-Fi 20 Max EQE and 2 GHz modulation.
  • To demonstrate and then manufacture monolithic on chip integration of µLEDs with DBRs and HEMTs for ultra high resolution ultra high efficient micro display (a pixel diameter of 5 µm and an inter pitch of 2 µm) and ultra fast 2 GHz) zero cross talk for Li-Fi.
  • To establish and then develop a spinout into a global manufacturer of monolithic on chip integration systems.

Major Challenges

  • The development of compatible flip chip processes for monolithic on chip integration
  • Further strain engineering by using an extra mediate layer
  • A combination of MOVPE and MBE to integrate III nitrides with GaAsP AlGaAsP on patterned substrates

Progress and Achievements

  • Developed a patented approach to on chip epitaxial integration of µLED arrays
  • Demonstrated ultra small and ultra compact µLED arrays with a record EQE and the narrowest spectral linewidth (µLEDs with 3.6 µm in diameter, 2 µm in inter pitch and 9.5 Max EQE)
  • Demonstrated 1 st monolithic on chip epitaxial integration of µ LEDs/HEMTs with a record modulation bandwidth of 1 GHz
  • Demonstrated GaN HEMTs with a record highest breakdown field 2 5 MV/cm), extremely low leakage current 100 nA / and excellent Figure of Merit 1313×108 V 2 Ω · cm2
  • Developed a patent approach to achieving a non polar GaN photodetector exhibiting exhibits a record high responsivity which is 4 orders of magnitude higher compared with the current state of the art, and a record fast response time which is three orders of magnitude faster than the current state of the art

So far, WP 6 has led to:

  • 3 plenary talks, 6 invited talks, 32 journal papers and 42 conference papers
  • 4 IP Patents
  • the organisation of the 3 rd Industrial Event, attracting 15 industrial companies
  • As a result of the innovation of from WP 6 Epipix the Sheffield’s spin out dedicating epitaxial integration of µ LEDs/HEMTs, has been officially founded on 20 th Jan 2020 currently finalising £10M investment

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