GeSn/Ge multiquantum well photodetectors on Si substrates

Abstract

Vertical incidence GeSn/Ge multiquantum well (MQW) pin photodetectors on Si substrates were fabricated with a Sn concentration of 7%. The epitaxial structure was grown with a special low temperature molecular beam epitaxy process. The Ge barrier in the GeSn/Ge MQW was kept constant at 10 nm. The well width was varied between 6 and 12 nm. The GeSn/Ge MQW structures were grown pseudomorphically with the in-plane lattice constant of the Ge virtual substrate. The absorption edge shifts to longer wavelengths with thicker QWs in agreement with expectations from smaller quantization energies for the thicker QWs.

Short-range atomic ordering in nonequilibrium silicon-germanium-tin semiconductors

“…This phenomenon manifests itself when at least one of the elements forming the alloy preferentially occupies or avoids specific lattice sites. This induces short-range order in the lattice with an impact on the basic properties of the alloyed semiconductors [3][4][5][6][7].The recent progress in developing Sn-rich group IV (SiGeSn) ternary semiconductors and their integration in a variety of low dimensional systems and devices have revived the interest in elucidating the atomistic-level properties of monocrystalline alloys [9][10][11][12][13][14][15][16][17][18][19][20]. Interestingly, unlike…”

“…The recent progress in developing Sn-rich group IV (SiGeSn) ternary semiconductors and their integration in a variety of low dimensional systems and devices have revived the interest in elucidating the atomistic-level properties of monocrystalline alloys [9][10][11][12][13][14][15][16][17][18][19][20]. Interestingly, unlike III-V semiconductors, achieving a direct bandgap in Si Ge…”

Si based GeSn photoconductors with a 1.63 A/W peak responsivity and a 2.4 μm long-wavelength cutoff

“…Active photonic Ge 1-x Sn x devices such as light emitting diodes, 5-8 photoconductors, [9][10][11] and photodiodes 12,13 demonstrate that high quality growth can be achieved from both CVD 14 and MBE systems. 9,10 Photoconductors are advantageous for early detector technology development due to the low background doping concentrations and reduced fabrication complexity.…”

Direct bandgap GeSn light emitting diodes for short-wave infrared applications grown on Si

“…Therefore the devices, being light emitters in forward regime, are in principle also able to act as light detectors under reversed bias, as shown for GeSn in different detector designs. [17][18][19] In the inset, the same measurement is shown in log-log scale also for lower temperatures. A clear curving in the forward regime can be observed when lowering the temperature down to 200 K. This curving is linked to a regime of negative differential resistance, which has already been observed in similar GeSn devices at temperatures below about 140 K.…”