Response to “Comment on ‘Some considerations concerning the detection of excitons by field ionization in a Schottky barrier’” – [phys. stat. sol. (b)239, No. 1, 257–260 (2003)]

Abstract

A photocurrent signal and its temporal dependence on the excitation conditions observed in a Cu/Cu 2 O Schottky barrier after pulsed illumination of the Cu 2 O crystal has been used to claim excitonic superfluidity and Bose-Einstein condensation. See, e.g., E. Benson, E. Fortin, and A. Mysyrowicz [phys. stat. sol. (b) 191, 345 (1995)]. C. Klingshirn, T. Fleck, and M. Jörger [phys. stat. sol. (b) 234, 23 (2002)] showed that a similar behaviour can be expected also from detector saturation which is very likely for the excitation conditions used in the above work. In the above comment [phys. stat. sol. (b) 239, 257 (2003)], these arguments have been rejected, based on new experiments under resonant exciton creation. In this response we show that the excitation conditions used in these new experiments do not allow to question the statements in favour of detector saturation, but raise some additional questions.

Study of the 1s orthoexciton luminescence in Cu2O under two-photon excitation

“…Reports of 1s yellow paraexciton Bose-Einstein condensation (BEC) [4] and superfluidity [5], and 1s orthoexciton BEC [6] have attracted much attention. However, each of these experiments now has an alternative explanation [7][8][9][10][11][12] which leaves it an open question as to whether excitonic BEC and superfluidity has been, or can be, realized in Cu 2 O. Recent research has been directed toward finding different approaches to investigate this question.…”

Exciton transport and intersubband transitions in Cu2O

“…These quantities are also interesting for the question if excitonic Bose-Einstein condensation can be reached in this material, a question, which is also discussed controversially since decades (see e.g. [1,4] and references therein). There are various means to determine the lifetime of excitons.…”