Optimizing photocurrent intensity in layered SiGe heterostructures

Abstract We study the dependence of photo-spectral intensity on tri- and multilayers of SiO 2 /[SiGe [ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>d</mml:mi> <mml:mrow> <mml:mi>SiGe</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ]/SiO 2 ] N with repetitions N = 1 to 10 and thicknesses <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>d</mml:mi> <mml:mrow> <mml:mi>SiGe</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:math> –100 nm. Photocurrent analysis reveals a bimodal spectral feature. A comparison of the photocurrent analysis between tri- and multilayers shows that in the multilayer structures, the photo-spectral intensity increases with increasing repetition N . The change in intensity could then be further tuned by changing the thickness of the SiGe layers <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>d</mml:mi> <mml:mrow> <mml:mi>SiGe</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> . We attribute the change in intensity to an increase in tensile strain, along with increased Ge atomic concentration and reduced SiGe-nano cluster size.