The emission mechanisms of strainedInxGa1−xNquantum wells (QWs) were shown to vary depending on the well thickness,L, andx. The absorption edge was modulated by the quantum confined Stark effect and quantum confined Franz-Keldysh effect (QCFK) for the wells, in which, for the first approximation, the product of the piezoelectric field,FPZ,andLexceed the valence band discontinuity,&Dgr;EV.In this case, holes are confined in the triangular potential well formed at one side of the well producing the apparent Stokes-like shift. Under the condition thatFPZ×Lexceeds the conduction band discontinuity&Dgr;EC,the electron-hole pair is confined at opposite sides of the well. The QCFK further modulated the emission energy for the wells withLgreater than the three dimensional free exciton Bohr radiusaB.On the other hand, effective in-plane localization of carriers in quantum disk size potential minima, which are produced by nonrandom alloy compositional fluctuation enhanced by the large bowing parameter andFPZ,produces a confined electron-hole pair whose wave functions are still overlapped (quantized excitons) provided thatL<aB.©1998 American Institute of Physics.&hthinsp;