Electronic transport in modulation-doped InSb quantum well heterostructures

Abstract

The mobility and carrier concentration of a number of InSb-based modulation-doped quantum well heterostructures are examined over a range of temperatures between 4.5 and 300 K. Wide well ͑30 nm͒ and narrow well ͑15 nm͒ structures are measured. The temperature dependent mobilities are considered within a scattering model that incorporates polar optical and acoustic phonon scatterings, interface roughness scattering, and scattering from charged impurities both in the three-dimensional background and within a distributed "quasitwo-dimensional" doping layer. Room temperature mobilities as high as 51 000 cm 2 / V s are reported for heterostructures with a carrier concentration of 5.8ϫ 10 11 cm −2 , while low-temperature mobility ͑below 40 K͒ reaches 248 000 cm 2 / V s for a carrier concentration of 3.9ϫ 10 11 cm −2. A Schrödinger-Poisson model is used to calculate band structures in the material and is shown to accurately predict carrier concentrations over the whole temperature range. Low-temperature mobility is shown to be dominated by remote ionized impurity scattering in wide well samples and by a combination of ionized impurity and interface roughness scattering in narrow well samples.

Suppression of the parasitic buffer layer conductance in InSb/AlxIn1−xSb heterostructures using a wide-band-gap barrier layer

“…In this way, subsequent growth of InSb QWs with high mobilities is achieved with remote delta doping (in the range 10-40 m 2 /Vs at 2 K and 4-6 m 2 /Vs at 300 K). 8,9,21,22 Here, we study the electronic properties of two sets of modulation doped InSb/Al x In 1-x Sb QW heterostructures grown by molecular beam epitaxy onto semi-insulating GaAs undoped spacer layer. The two MBL samples differ from each other only in top cap thickness and Te-doping density (fixed spacer thickness) with MBL-2 having a thinner top cap with a nominally higher doping density than MBL-1.…”

“…21,42 For narrow 15-nm InSb QWs, mobilities are typically lower (7-11 m 2 /Vs at 2 K), and it was found that interface roughness scattering adds a significant contribution to the total scattering rate. 42 It follows that interface roughness scattering may also play a role in our samples. A second effect is also relevant.…”

“…Calculations of the mobility in a set of equivalent InSb/AlInSb QWs were recently performed by Orr et al 42 and Pooley et al 21 In wide 30-nm InSb QWs, typical mobilities are in the range 20-40 m 2 /Vs at 2 K and found to be limited by scattering from ionized impurities in the remote δ-doped layer. 21,42 For narrow 15-nm InSb QWs, mobilities are typically lower (7-11 m 2 /Vs at 2 K), and it was found that interface roughness scattering adds a significant contribution to the total scattering rate. 42 It follows that interface roughness scattering may also play a role in our samples.…”

“…The two-dimensional electron gases (2DEGs) formed in narrow band-gap III-V semiconductors offer the largest mobilities and saturation velocities at RT owing to a light effective mass. Electron mobilities of 4 m 2 /Vs are routinely obtained in modulation doped InSb/Al x In 1-x Sb quantum well (QW) structures, 7,8 with a highest value of 6 m 2 /Vs reported in 30-nm-wide InSb QWs. 9 State-of-the-art n and p-type InSb QW-field effect transistors (FETs) with sub-100-nm gate lengths have been demonstrated with record f T cutoff frequencies as a result.…”

Interplay of spin and orbital magnetogyrotropic photogalvanic effects in InSb/(Al,In)Sb quantum well structures

“…4 This novel material is the subject of numerous experimental studies of transport, optical, magneto-optical, and spin-related phenomena. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The characteristics driving the interest in this novel narrow gap material are the high carrier mobility, small effective masses, large Landé g * factor, possibility of the mesoscopic spindependent ballistic transport, and a strong spin-orbit coupling. The latter gives rise to a number of optoelectronic effects such as, e.g., terahertz photoconductivity 15 and the circular photogalvanic effect [16][17][18][19][20][21][22] recently observed in InSb QWs.…”