The concept of high-efficiency, high-reliability and low-threshold electrically pumped lasers monolithically grown on silicon has attracted great attention over the past several decades, as a promising on-chip optical source for Si photonics. In this paper, we report an electrically pumped continuous-wave (CW) 1.3 mu m InAs/GaAs quantum dot (QD) lasers grown on a complementary metal-oxidesemiconductor (CMOS) compatible Si exact (0 0 1) substrate with reduced GaAs buffer thickness down to similar to 2 mu m. A threshold current density (Jth) as low as similar to 160 A/cm(2) has been achieved at room temperature. The characteristic temperature (T-0) obtained is similar to 60.8 K and laser operation is observed up to 52 degrees C under CW mode. These results suggest that an O-band InAs/GaAs QD laser could be very promising to develop a monolithically integrated on-chip optical source for Si photonics.