Growth temperature effects on the optical properties of Si modulation-doped InxGa1-xAs/InyAl1-yAs/InP heterostructures

High electron mobility transistor (HEMT) devices based on InxGa1 - xAs/InyA l1 - xAs matched channels are characterized using photoluminescence (PL) sp ectroscopy. They have been grown by molecular beam epitaxy (MBE) on InP sub strates at different well growth temperatures T-g ranging from 470 to 530 d egrees C. Optical properties of the two dimensional electron gas (2DEG) in the InxGa1 - xAs channel are investigated and have been analyzed using a se lf-consistent calculation of the sub-band structure. Two main features are revealed from this analysis: (i) in the InxGa1 - xAs channels grown at 530 degrees C, the luminescence predominantly arises from the confined 2DEG and (ii) low T-g favours the radiative recombination between trapped electrons and photogenerated holes. Correlation between PL results and Hall mobility measurements performed on the HEMTs studied has been made in order to expl ain the effects of the well growth temperature T-g on the optical behaviour of these devices. The luminescence related to the InxGa1 - xAs channel has been investigated versus the power excitation as well. It was found that t his luminescence does not show either a significant energy shift, nor a bro adening near the Fermi edge. The latter behaviour excludes the possibility of the localization of photocreated holes in the channel epilayer. A detail ed analysis and attempts of explanations of all these results will be prese nted. (C) 2000 Elsevier Science B.V. All rights reserved.