The backlight is white LED, so that is your best bet.  
I am using a Calibrite colorchecker display (x-rite) calibration device to calibrate the screen of an Inspiron 14 7400 laptop (non-touch). The Calibrite software (ccStudio) needs to know the type of screen, with the choices: Generic, CCFL, Wide Gamut CCFL, White LED, RGB LED, OLED, Plasma, GB-LED, Projector, PFS Phosphor. I can't find the necessary information on the screen type for this model of laptop. On the purchase order the screen part has the code: 391-BFLP and the details: 14.5-inch 16:10 QHD+ (2560 x 1600) IPS AG Non-Touch, 300nits, 100% sRGB. So it is an IPS monitor screen, but I still don't know which option to select. Calibrite says contact DELL. Hope someone can help!   
Screen calibration of Inspiron 14 7400 laptop