Next generation white lighting and displays request a combination of high efficient RGB (Red, Green, Blue) or RGYB (Red, Green, Blue, Yellow) LEDs as opposed to current white LEDs fabricated using the "blue LED +yellow phosphor" approach. A white lighting source fabricated in either a RGB or a RGBY manner could potentially provide not only highest efficiency but also best colour rendering. The utilisation of discrete wavelength LEDs would also provide a best approach to tuning colour temperature in order to replicate the colour temperature of the Sun. Furthermore, a polarized backlight used as displays is necessary, while the current approach is to use a polarizing filter to polarize the light from current c-plane LEDs in order to achieve polarized light, leading to around 30% energy waste and thus very inefficient. Current white LEDs for lighting or displays are based on c-plane LEDs grown on (0001) sapphire substrates which is along a polar orientation, thus suffering from spontaneous and piezoelectric polarizations and thus less efficient. In addition, the epitaxial growth of GaN along the polar orientation also leads to an intrinsically low efficiency in indium incorporation into GaN and as a result it would be a great challenge to achieve long emission wavelength such as green and yellow emitters, generating the well-known "green/yellow" gap. The emission from current InGaN based LEDs exhibits unpolarized features.