InGaN Color Tunable Full Color Passive Matrix
Matthew Hartensveld
Abstract
A single material solution to a full color micro light emitting diode ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED) display has remained elusive due to distinct material differences of each color, along with the difficulties of integration. To address this an Indium Gallium Nitride (InGaN) passive matrix array is fabricated with color tunable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs from red at 640 nm to blue at 425 nm. The presented arrays build upon the initial work with V-groove color tunable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs to explore applications in displays. Initial 5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times5$ </tex-math></inline-formula> arrays of 20 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}^{{2}}~\mu $ </tex-math></inline-formula> LEDs are fabricated through etching the Gallium Nitride (GaN) down to the sapphire substrate to form electrically isolated n-GaN columns with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LEDs, while a spacer dielectric and indium tin oxide (ITO) layer form the anode rows. Color tunability and color mixing were demonstrated, where a single <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED can act as a complete pixel. Different emission colors were demonstrated from the array including red, yellow, green, and blue. This work forms the basis on which V-groove technology can further expand into <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED displays to solve the problem of a single material solution.