Semiconductor light emitting device, backlight, color image display device and phosphor to be used for them

A semiconductor light emitting device, comprising:

• a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination,
• wherein the phosphors comprise a green emitting phosphor having at least one emission peak in a wavelength region of from 515 to 550 nm and a red emitting phosphor having at least one emission peak with a half-value width of at most 10 nm in a wavelength region of from 610 to 650 nm;
• the red emitting phosphor has substantially no excitation spectrum in the emission wavelength region of the green emitting phosphor and comprises Mn4+ as an activated element;
• the green emitting phosphor and the red emitting phosphor have the variation rate of the emission peak intensity at 100° C. to the emission intensity at 25° C. of at most 40%, when the wavelength of the excitation light is 400 nm or 455 nm;
• and
• wherein the red emitting phosphor comprises a crystal phase having a chemical composition represented by the following formula (1′), wherein the proportion of Mn based on the total mols of MIV′ and Mn is at least 0.1 mol % and at most 6 mol %, and the specific surface area is at most 1.3 m2/g:
• MI′2MIV′F6:R (1′)
• wherein
• MI′ is at least one element selected from the group consisting of K and Na,
• MIV′ is at least one metal element selected from the group consisting of Groups 4 and 14 of the Periodic Table comprising at least Si, and
• R is an activated element comprising at least Mn, and
• wherein thermally decomposed F amount per 1 g of the red emitting phosphor is at most 2 μg/min.