Effects of buffer layers on the structural and electronic properties of InSb films

Abstract

Effect of material properties on low-energy electron transmission in thin chemical-vapor deposited diamond films J. Appl. Phys. 97, 093717 (2005); 10.1063/1.1893212 Improved pseudomorphic high electron mobility transistor structures on InGaAs substratesWe have investigated the effects of various buffer layers on the structural and electronic properties of n-doped InSb films. We find a significant decrease in room-temperature electron mobility of InSb films grown on low-misfit GaSb buffers, and a significant increase in room-temperature electron mobility of InSb films grown on high-misfit InAlSb or step-graded GaSb+ InAlSb buffers, in comparison with those grown directly on GaAs. Plan-view transmission electron microscopy ͑TEM͒ indicates a significant increase in threading dislocation density for InSb films grown on the low-misfit buffers, and a significant decrease in threading dislocation density for InSb films grown on high-misfit or step-graded buffers, in comparison with those grown directly on GaAs. Cross-sectional TEM reveals the role of the film/buffer interfaces in the nucleation ͑filtering͒ of threading dislocations for the low-misfit ͑high-misfit and step-graded͒ buffers. A quantitative analysis of electron mobility and carrier-concentration dependence on threading dislocation density suggests that electron scattering from the lattice dilation associated with threading dislocations has a stronger effect on electron mobility than electron scattering from the depletion potential surrounding the dislocations. Furthermore, while lattice dilation is the predominant mobility-limiting factor in these n-doped InSb films, ionized impurity scattering associated with dopants also plays a role in limiting the electron mobility.

Comparison of MBE Growth of InSb on Si (001) and GaAs (001)

“…Electrons can be scattered by the depletion potential around the dislocations and the lattice dilatation associated with the dislocations. Using the Pödör and Dexter-Seitz models, 20,21 Weng et al 1 found that the dominant factor limiting the electron mobility was the lattice dilatation scattering, which is apparently consistent with the predictions of the Dexter-Seitz model. According to this model, the mobility limited by deformation potential scattering l d is inversely proportional to the edge dislocation density D. These results, therefore, show a quantitative correlation between increasing dislocation density and decreasing electron mobility.…”

“…This highest mobility was higher than the mobilities reported for 2 lm MBE InSb grown directly on GaAs samples done by other groups. 1,22 The samples grown at 350°C and 370°C showed the same carrier concentration at low temperatures (Fig. 2, green and orange curves)-thus the same number of ionized impurities-but markedly different mobilities.…”

“…At this point, the initially strained film would ideally decompose to a relaxed structure where the generated dislocations relieve a portion of the misfit. The large mismatch between the InSb film-and GaAs substrate-introduced misfit and threading dislocations has been investigated and reported by Weng et al 1,16 In the case of InSb/Si, it is much more difficult to obtain a good crystal quality of InSb film with a smooth surface. To improve the crystal quality, we applied several techniques.…”

Micro‐twin induced structural misalignment in InSb quantum wells

“…The incorporation of InSb/Al x In 1-x Sb interfaces [5,6] and Al x In 1-x Sb/Al y In 1-y Sb interfaces [8,9] in an Al x In 1-x Sb buffer layer is effective in reducing the TD density in an InSb QW [5,6,8,9] and an InSb epilayer [10]. The density of MTs in InSb QWs can be suppressed to an order of 10 2 /cm by the use of 2° off-axis GaAs (001) substrate [7].…”

Monolithic Integration of an Active InSb-Based Mid-Infrared Photopixel With a GaAs MESFET

“…The barrier layer between the p+ and the absorption layer was grown since it has been reported to block the flow of electrons between the two layers, therefore reducing the diode leakage and allowing operation at higher temperature [16]. The n-contact layer of the InSb photodiode was chosen to be 3 μm thick in order to further reduce the number of defects and threading dislocations, that tend to appear much more frequently near to the interface between the GaSb buffer and the InSb [17]. The InSb materials were etched using a citric acidhydrogen peroxide etchant (33:2:80 C 6 H 8 O 7 :H 2 O 2 :H 2 O by weight) to define the 45 µm diameter active area of the InSb photodiode at a rate of 20 nm/min.…”