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A solution of resonant tunneling problem in multilayered heterostructures is presented based on the quantum mechanical wave impedance concept. The transmission matrix is found using open and short circuit tests. By using the transmission matrix approach the transmissivity of the structure is determined as a function of the incident electron energy. The J-V curves are obtained by using this approach and the results compare to previous models with good agreement. The method was then applied to a new quantum well three barrier structure, where the inner barrier height is variable. It is found that increasing the inner barrier height causes the resonance energies to align, meaning that coupling between the wells increases. By using this method, the analysis and tunneling current calculations of any structure can be easily figured and new tunneling quantum well devices can be designed.

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We have measured electron and hole multiplication factors and impact ionization coefficients in 550 Å GaAs/500 Å Al0.3Ga0.7As quantum wells with an intermediate Al0.45Ga0.55As barrier (50 and 100 Å) inserted in the well region. It is seen that while the measured value of α(E) is insensitive to the position of the intermediate barrier in the well, the value of β(E) is very sensitive. The value of α/β varies from less than unity to 5, depending on the position of this barrier. These results suggest that hole confinement and scattering play a major role in making the value of α/β greater than unity in these multilayered structures.

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ABSTR ACTTWO different integration schemes for front-end optical receivers have been demonstrated for GaAs and InP-based material systems. An InP-based PIN-FET vertically integrated circuit exhibits a bandwidth greater than 2 GHz. The FET exhibits an extrinsic g, = 450mS/mm and f~ = 9GHz. The GaAs-based planar structure consists of a modulated barrier photodiode and a doped channel FET made with the same epitaxial layers. The detector has an optical gain of 200 and the FET performance is characterized by g, = 250mS/mm, fT = 12GHz and fmaz = 21GHz.

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