Determination of built-in electric fields in quaternary InAlGaN heterostructures

A study of internal electric field contribution to the light emission mechanism of InAlGaN based multiquantum wells was performed. To determine the magnitude of the built-in electric field we employed: (i) theoretical estimation of the piezoelectric and spontaneous polarizations, (ii) analysis of the emission energy as a function of the quantum well width, (iii) hydrostatic pressure experiments, and finally (iv) measurements of photoluminescence decay. Performed calculations gave high magnitude of the built-in electric field. On the contrary, independently of the quantum well width the pressure shift of the light emission energy and the photoluminescence decay time showed almost constant values. These observations are interpreted as evidence of a lack of the built-in electric field in the used quaternary quantum wells. Possible reasons for the controversies between theory and experiment are suggested.