For several months, iPhone 6 rumors continued to pour in over the speculation that Apple is currently testing various concepts for its upcoming smartphone. The latest rumor says that Apple is working with Sharp to develop an HD Retina display that will include IGZO technology.

Sharp's IGZO technology could possibly be incorporated into the build of iPhone 6. IGZO is a semiconductor material made for LCD displays and stands for indium gallium zinc oxide. Apple knows it has to wow consumers to take the attention away from rivals Samsung and HTC. Improvements on its Retina display will help challenge the 1080p full HD displays on the Galaxy S4 and HTC One.

Rumors suggest that an iPhone 6 prototype conceptualizes a Retina+ Sharp IGZO display, more than likely with a 1080p resolution. The revamped display would offer users more accurate touch responsiveness and more power efficiency. During CES 2013, Sharp introduced its IGZO technology on its latest 5-inch smartphone with an HD resolution of 720p.

"IGZO has the potential to be a groundbreaking technology," said Hiroshi Hayase, a Tokyo-based analyst for the research firm NPD DisplaySearch.

Apple is allegedly experimenting with various prototypes and concepts, along with higher resolution displays. Apple also might offer two size variants for the screen size so customers can choose between large and small. Apple may also follow the Galaxy Note trend and include a working stylus or pencil with its iPhone 6 smartphone, but we'll most likely see this in 2014. Other Apple iPhone 6 concepts include a possible flexible wrap-around display and even a transparent display.