In:
MRS Proceedings, Springer Science and Business Media LLC, Vol. 832 ( 2004)
Abstract:
The primary challenges in implementing a Si based quantum cascade laser are discussed. Intersubband absorption measurements were carried out on a series of modulation doped multiquantum well structures. The spectra were compared to the predictions of a 6 band k.p model, which confirmed the excellent accuracy of the model, and its ability to predict the bandstructures of more complicated cascade structures. A detailed structural analysis demonstrated excellent growth quality, with an interface roughness of 〈 0.4 nm. Electroluminescence measurements on cascade structures with doped contacts, processed as finger structures and waveguides of various sizes, enabled a quantitative analysis of the active region performance. The upper state lifetime τ nr was ∼ 100 fs, leading to a total active region optical gain of ∼ 2 cm −1 , a factor of ∼ 10 lower than the estimated total losses due to free carrier absorption. The total emitted power and the linewidth of the intersubband emission saturate above ∼ 6.5 kA/cm 2 , probably due to misalignment of the injector levels at high biases. The effect of leak currents and interspersed light hole states on the intersubband emission are considered.
Type of Medium:
Online Resource
ISSN:
0272-9172
,
1946-4274
DOI:
10.1557/PROC-832-F4.2
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2004