The opposing demands of increasing image quality and reducing power consumption in mobile device displays create an extremely demanding performance and manufacturability standard for thin film electronics.

• Increasing image quality requires smaller and faster thin film transistors capable of producing enough current to meet OLED and microLED luminosity specifications at >120Hz image refresh rate.

• Reducing power consumption requires faster thin film transistors that also have very low leakage current to support a <0.1Hz image refresh rate.

The display industry’s response to these opposing demands is the low temperature polycrystalline oxide (LTPO) pixel circuit - using LTPS TFTs for the OLED and microLED drive current, and IGZO TFTs for the drive switching function. However, the integration of LTPS and IGZO TFTs into one manufacturing process presents materials-level issues in addition to LTPS Vth drift and off-state current leakage issues and mobility limitations of existing IGZO TFTs. LTPO - a great idea but very difficult to manufacture and severely hampered by the limitations of LTPS and IGZO TFTs.