An IGZO display is any display panel that uses indium gallium zinc oxide or IGZO as the primary semiconducting material in its thin-film transistor or TFT. Hence, it is not a display technology but rather, a specific backplane technology for driving and addressing transmissive or emissive components of a particular panel.
Some of the notable examples of a display technology include LCD technologies such as in-plane switching or IPS LCD and twisted nematic or TN LCD, as well as organic light-emitting diode or OLED technology, and microLED technology. On the other hand, there are three major backplane technologies: IGZO TFT, amorphous silicon or a-Si TFT, and low-temperature polysilicon or LTPS TFT.
Understanding the Pros and Cons of IGZO Display
Below are the advantages and applications of backplane technology based on indium gallium zinc oxide:
• Note that a-Si-TFT is not transparent but can be stretched thin enough to allow an adequate amount of light to pass through. An IGZO-TFT is naturally transparent, thus translating to specific advantages such as brighter display panels and energy efficiency, reduced need for backlighting in the case of LCDs, and reduced brightness output in OLED and LED displays.
• Another advantage of IGZO display is that it has 30 to 50 times more electron mobility than a-Si display. Better electron flow means higher resolutions and faster pixel response time to allow the manufacturing of smaller panels with high pixel density. Earlier prototypes using indium gallium zinc oxide featured a 6-inch panel at 2560×1600 pixels or 498 pixels per inch.
• Note that transparency and better electron mobility also mean that these displays are more power-efficient than those based on amorphous silicon. Furthermore, it has a lower leakage current than both amorphous and low-temperature polysilicon TFT, thus allowing it to retain an active pixel state longer, especially when displaying still images such as photographs and documents.
• An indium gallium zinc oxide is also an intermittent type of semiconductor. It does not need continuous drive. Hence, in touch-based panels, another advantage is that it is more sensitive than a-Si and LTPS. It can mimic natural handwriting input because it can pick up lines as sensitive as the tip of the pen. Writing on this panel using a stylus would have a closer feel as on paper.
The following are the disadvantages and limitation of backplane technology based on indium gallium zinc oxide:
• Note that indium gallium zinc oxide is a metal oxide. High reactivity to oxygen may result in very low voltage sensitivity. Thereby, due to possible oxidation, this semiconductor can age faster than a-Si and LTPS, as evident from its diminishing voltage sensitivity or capacity to become responsive to the application of voltage.
• Manufacturing IGZO displays also require the use of rare-earth materials. More specifically, indium and gallium are rare. They are costly to extract from their point of origin and procure from the suppliers. This drawback introduces cost and supply risks for manufacturers of display panels and consumer electronic devices.
• Another disadvantage is that producing displays based on this semiconductor is more complicated than manufacturing a-Si TFT display panels. The current challenge to mass-producing indium gallium zinc oxide is the relevant synthesis method using Pulsed Laser Deposition or PLD. However, PLD requires expensive equipment and lengthier time. These requirements can hamper large-scale production.
• It is also worth mentioning that LTPS displays have key advantages over IGZO displays and a-Si displays. More specifically, it has better and faster electron flow, allows the production of small-sized screens with high pixel density, and more efficient power consumption.
FURTHER READINGS AND REFERENCES
- Bo, X-Z., Yao, N., Shieh, S. R., Duffy, T. S., and. Sturm, J. C. 2002. “Large-Grain Polycrystalline Silicon Films with Low Intragranular Defect Density by Low-Temperature Solid-Phase Crystallization Without Underlying Oxide.” Journal of Applied Physics. 91(5): 2910-2915. DOI: 1063/1.1448395
- Bonheur, K. 2019. “Advantages and Disadvantages of LTPS LCD.” Profolus. Available online
- Bonheur, K. 2020. “Advantages and Disadvantages of LTPS LCD.” Profolus. Available online
- Chang, T-C., Tsao, Y-C., Chen, P-H., Tai, M-C., Huang, S-P., Su, W-C., and Chen, G-F. 2020. Flexible Low-Temperature Polycrystalline Silicon Thin-Film Transistors. Materials Today Advances. 5: 100040. DOI: 1016/j.mtadv.2019.100040
- Miyata, Y., Furuta, M., Yoshioka, T., and Kawamura, T. 1992. “Low-Temperature Polycrystalline Silicon Thin-Film Transistors for Large-Area Liquid Crystal Display.” Japanese Journal of Applied Physics. 31(P. 1, No. 12B): 4559-4562. DOI: 1143/jjap.31.4559