Growth of HgTe Quantum Wells for IR to THz Detectors

Abstract

We zone-engineered HgCdTe/HgTe/HgCdTe quantum wells (QWs) using the molecular-beam epitaxy (MBE) method with in situ high-precision ellipsometric control of composition and thickness. The variations of ellipsometric parameters in the w-D plane were represented by smooth broken curves during HgTe QW growth with abrupt composition changes. The form of the spiral fragments and their extensions from fracture to fracture revealed the growing layer composition and its thickness. Single and multiple (up to 30) Cd x Hg 1Àx Te/HgTe/Cd x Hg 1Àx Te QWs with abrupt changes of composition were grown reproducibly on (013) GaAs substrates. HgTe thickness was in the range of 16 nm to 22 nm, with the central portion of Cd x Hg 1Àx Te spacers doped by In to a concentration of 10 14 cm À3 to 10 17 cm À3 . Based on this research, high-quality (013)-grown HgTe QW structures can be used for all-electric detection of radiation ellipticity in a wide spectral range, from far-infrared (terahertz radiation) to mid-infrared wavelengths. Detection was demonstrated for various low-power continuous-wave (CW) lasers and high-power THz pulsed laser systems.

Исследования волноводных структур с квантовыми ямами на основе HgCdTe для получения длинноволнового стимулированного излучения

“…Нанофизика и наноэлектроника" 1617 ричесим контролем состава и толщины слоев [14,15]. Как показано в работах [14,15], данный подход, развитый лишь относительно недавно, позволяет контролировать толщину КЯ вплоть до одного монослоя.…”

“…Как показано в работах [14,15], данный подход, развитый лишь относительно недавно, позволяет контролировать толщину КЯ вплоть до одного монослоя. Квантовые ямы HgTe/CdHgTe обладают рядом уни-кальных свойств, обусловленных, в частности, тем, что при уменьшении ширины КЯ можно осуществить пере-ход от инвертированной зонной структуры (наследуемой в широких КЯ от объемного HgTe), к нормальной через возникающий при некоторой критической толщине КЯ " графеноподобный" закон дисперсии [16].…”

Electron relaxation and mobility in the inverted band quantum well CdTe/Hg1-xCdxTe/CdTe

“…The concentration of charged impurities in these QWs can be about 10 14 -10 16 cm -3 [6,7,16]. Due to the inverted band scheme and high density of states for heavy holes, the Fermi level lies higher than the bottom of the conduction band in the well.…”

“…Photoluminescence [4,5] and photoconductivity [6] of Hg 1-x Cd x Te QWs grown on different substrates (Si, GaAs, ZnTe, CdTe) have been studied. It is shown in [7] that high-quality HgTe QW structures can be used for all-electric detection of radiation ellipticity in a wide spectral range, from far-infrared to mid-infrared wavelengths. Measurements of electrical conductivity, the Hall coefficient, and photoluminescence of ion-milled Hg 1-x Cd x Te films were performed in [8].…”

Nonlinear terahertz response of HgTe/CdTe quantum wells

“…14 Optical conductivity of HgTe/CdTe QWs has long been an interesting topic since the tunable band gap can give rise to optical response in the terahertz-far infrared regime, a technologically important frequency window. Optoelectronic devices such as THz detectors and emitters 15,16 have applications in many areas of science and industry. It has been demonstrated that HgTe/CdTe superlattices have significant non-linear optical properties such as large v (3) , THz response, and high saturation threshold.…”