Singular instabilities at crystal growth interfaces of group‐IV and III‐V semiconductors lead to as‐grown surfaces optical devices, however, requirethe achievement of smoth planar layers. We consider the stability of surfaces with respect to singular instabilities and show that stable planar growth interfaces occur at slight deviati8ons from the singular orientation where monatomic growth steps are uniformly arrayed to minimize the interfacial energy resulting from step‐step attractive interactions. These results are applied to the elimination of crystal growth terraces in LPE AlGaAs‐GaAs laser material. Similar considerations appear to explain pyramid formations on CVD Si and on MBE InP.