Light emitting devices (LEDs) are described. An LED includes a light emitting semiconductor structure that includes a light emitting active layer disposed between an n-layer and a p-layer. A wavelength converting material may be disposed adjacent the light emitting semiconductor structure. The wavelength converting material includes multiple pores, at least one of which contains a second material. An absolute value of a ratio of a coefficient of thermal expansion of the second material to a coefficient of thermal expansion of the wavelength converting material is at least two in an embodiment, at least ten in another embodiment, at least 100 in another embodiment, and at least 1,000 in yet another embodiment.