“Among the different types of biometric sensors that Samsung is testing for its Galaxy S5, the tech giant will go for fingerprint authentication rather than unintuitive user experience of iris recognition,” said an industry source who declined to be named.
“Who would want to put their handset up close to their eyes for authentication in places like movie theaters and bed, or even while they are driving?,” the source added.
Samsung is apparently working towards offering fingerprint sensors under the display panel so you could press your fingertip to the screen for scanning. Apple's implementation requires a user press their fingertip to the home button for scanning.
Another reason why the iris scanner will probably not be installed in the Galaxy S5 is the need for a third camera module which will make the device thicker and require a different design.
More details in the full report linked below...