Monolithic　integration　of　III-V　materials　and　devices　on　CMOS　compatible　on-axis　Si　(001)　substrates　enables　a　route　of　low-cost　and　high-density　Si-based　photonic　integrated　circuits.　Inversion　boundaries　(IBs)　are　defects　that　arise　from　the　interface　between　III-V　materials　and　Si,　which　makes　it　almost　impossible　to　produce　high-quality　III-V　devices　on　Si.　In　this　paper,　a　novel　technique　to　achieve　IB-free　GaAs　monolithically　grown　on　on-axis　Si　(001)　substrates　by　realizing　the　alternating　straight　and　meandering　single　atomic　steps　on　Si　surface　has　been　demonstrated　without　the　use　of　double　Si　atomic　steps,　which　was　previously　believed　to　be　the　key　for　IB-free　III-V　growth　on　Si.　The　periodic　straight　and　meandering　single　atomic　steps　on　Si　surface　are　results　of　high-temperature　annealing　of　Si　buffer　layer.　Furthermore,　an　electronically　pumped　quantum-dot　laser　has　been　demonstrated　on　this　IB-free　GaAs/Si　platform　with　a　maximum　operating　temperature　of　120　degrees　C.　These　results　can　be　a　major　step　towards　monolithic　integration　of　III-V　materials　and　devices　with　the　mature　CMOS　technology.