Photoluminescence (PL) studies were carried out on AlInGaN epilayers grown at different temperatures. An abnormal broad peak, which enhanced with the increase of Al incorporation, was observed below the band gap energy of AlInGaN in the 77K PL measurement. We assigned it to the non-optimum growth temperature for aluminum containing alloys since such emission can be suppressed at higher growth temperature. Thus, high temperature (HT) was proposed for AlInGaN growth. The quality of HT-grown quaternary AlInGaN alloys was superior to that of low-temperature-grown ones, their structural and optical properties are comparable to that of GaN. In addition, incorporating indium is also helpful to suppress this abnormal emission, which maybe due to the indium localization effect. Finally, high performance AlInGaN MQWs structure had also been demonstrated at a higher growth temperature. (C) 2004 Elsevier B.V. All rights reserved.