Heterostructure devices

Y. He, S. Gong, R. Hottori, and J. Kanicki, High performance organic polymer light-emitting heterostructure devices, Appl. Phys. Lett., 74 2265-2267, 1999. 

VG Kozlov, V Bulovic, PE Burrows, and SR Forrest, Laser action in organic semiconductor waveguide and double-heterostructure devices, Nature, 389 362-364, 1997. 

Several heterostructure geometries have been developed since the 1970s to optimize laser performance. Initial homojunction lasers were advanced by the use of heterostructures, specifically the double-heterostructure device where two materials are used. The ability of the materials growth technology to precisely control layer thickness and uniformity has resulted in the development of multiquantum well lasers in which the active layer of the laser consists of one or more thin layers to allow for improved electron and hole confinement as well as optical field confinement. 

However, not all excitons have sufficiently long lifetimes to reach the interface before recombining. To circumvent this problem and increase device efficiency, heterostructure devices have been fabricated. In these devices, donors and acceptors are mixed together to create a network that provides many internal interfaces where charge separation can occur. Heterostructure devices made from the donor polymer... 

The communications revolution also relies on a diverse set of CVD technologies. Some components are similar to those used in silicon microelectronics, but many are unique, involving complex epitaxial heterostructures of SiGe or compound semiconductor (e.g., AlGaAs) alloys that are required to yield high frequency (1-100 GHz) device operation. The communication revolution also relies on optoelectronic components, such as solid state diode lasers (another complex heterostructure device), and these devices are often grown by CVD. - Even the fiberoptic cables that transmit the optical component of the communications network are manufactured using a CVD technique to achieve the desired refractive index profile. ... 

R.A. Kiehl andT.C.L.G. Sollner, eds., High Speed Heterostructure Devices, Academic Press, Boston, 1994. 

Kiehl R A, Sollner T C L G (eds) (1994) High speed heterostructure devices. Academic, Boston... 

Recent developments in solid state solutions of AlN/SiC/InN/GaN open up the possibility of a new generation of heterostructure devices based on SiC. Single crystal epitaxial layers of AlN/SiC/InN have been recently demonstrated by Dmitriev [4]. A whole range of solid state solutions has been grown. Recently Dmitriev et al [5] reported on an (AlNx-SiC,.x)-(AlNySiC,.y) p-n junction. Solid state solutions of AlN-SiC [6,7] are also expected to lead to direct gap ternary materials for UV and deep blue optoelectronics, including the development of visible lasers. The direct to indirect bandgap transition is predicted to occur at between 70 and 80 % of AIN in SiC. 

Punkka E. and Rubner M.F., Molecular Heterostructure Devices Composed of Langmuir-Blodgett Films of Conducting Polymers, J. Electron. Mater. 21, 1057-1063, 1992. 

It has been shown that these strained-layers have unique optical and electronic properties (5,6). The band gap in these SLSs has been found to depend on the strain in the layers as well as the composition and layer thickness. Also, the energy of the band gap and the lattice constant of the SLS can be varied independently ( 7). Therefore, the use of SLSs either as a structural barrier to the propagation of misfit dislocations in mismatched systems or as "bulk" materials with unique properties, greatly increases the range of materials properties which can be used in heterostructure devices. 

The above devices, junction diodes, FET, lasers and ion implanted diodes, demonstrate that high quality devices can be made from SLS materials. Use of the unique properties of SLSs should greatly expand the areas of applications for heterostructure devices. 

Figure 2. Current-Voltage and Light-Voltage plot for an rrO/(PPV/SPS)5/(PPV MA)i5/Al heterostructure device. (Reproduced with permission from reference 15. Copyright 1996 Materials Research Society.)...

Polymer Semiconducting Heterostructure Devices by Nitrene-Mediated Photocrosslinking of Alkyl Side Chains. Nat. Mater. 2010,9,152-158. 

Owing to the additional confinement of carriers to within the quantum well structure, the resultant threshold current density becomes considerably less than for bulk double heterostructure devices. Additionally, quantum well lasers generally have a narrower gain spectrum (for similar bias currents to DH structures), a smaller lasing linewidth of the lasing modes, a reduced temperature dependence, and the potential for achieving higher modulation frequencies. 

Su N, Tang Y, Zhang Z, Fay P (2008) Observation and control of electrochemical etching effects in the fabrication of InAs/AlSb/GaSb heterostructure devices. J Vacuum Sci Technol B 26(3) 1025-1029... 

Fig. 4 Electroluminescent spectra of heterostructure device using PbBr-based layered perovskite a) single heterostructure device and b) double heterostructure device.

When the heterostructure EL devices were driven at 100 K, sharp EL due to exciton emission of CHEPbBr4 was observed. EL spectra of the heterostructure devices are shown in Fig. 4. 

Fig. 5 Current density-voltage characteristics of heterostructure devices using PbBr-based layered perovskite.

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