Luminescence from hot carrier interband recombination in wide InGaN quantum wells

Direct radiative recombination of high excited confined states across the band gap is observed as a broad emission band above the InGaN band edge in photoluminescence and electroluminescence for wide InGaN quantum wells (QWs). The observation of hot carrier interband recombination is possible in wide InGaN quantum wells because the transitions between the lower lying confined states are spatially indirect due to the piezoelectric field, and therefore become dark states with extremely low radiative transition rates at low carrier densities. Hot carrier luminescence was observed consistently for 7.8- and <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mn>25</a:mn> <a:mtext>−</a:mtext> <a:mi>nm</a:mi> </a:mrow> </a:math> -wide QWs at low and room temperature, while it is absent for a <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mrow> <b:mn>2.6</b:mn> <b:mtext>−</b:mtext> <b:mi>nm</b:mi> </b:mrow> </b:math> -thin QW. The spectrum of the emission is explained by <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:mi>k</c:mi> <c:mo>·</c:mo> <c:mi>p</c:mi> </c:mrow> </c:math> simulations assuming a weak dependency of the transition matrix element on the subband of the confined states, and a limited extent of carrier momentum around the <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mi mathvariant="normal">Γ</d:mi> </d:math> point.