High speed photoswitching: from material properties to device performances

Abstract

In this paper we show how the characteristics of semiconductor (SC) material with very short carriers trapping time impact the performances of ultrafast optoelectronic devices used for generation and detection of radiofrequency or TeraHertz signals. The impact of properties such as concentration of deep‐level trapping centres, free carrier drift velocity saturation and long time relaxation of deep‐level trapping centres are studied. For devices based on low‐temperature grown GaAs we observe that working above typical ratings in term of input optical power, laser repetition rate or biasing electrical field lead, to reduction of electrical signal bandwidth and amplitude and linearity of RF signal samplers. All our experimental results are sustained by numerical simulations that allow us to quantify the limitations induced by SC material properties. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)