P.A. Garbinski

Modulated barrier photodiode: A new majority‐carrier photodetector

A new majority‐carrier photodetector, called a modulated barrier photodiode (MBP), grown by molecular beam epitaxy has been developed. In sharp contrast to a bipolar phototransistor, the optical gain of MBP increases with decreasing incident power. An optical gain of 1000 at 1.5 nW incident power and a fall time of 600 psec have been obtained. In addition to the application for uses as a detector in an optical communication system, the device points to the feasibility of realizing a solid‐state triode.

Charge injection logic

The charge injection transistor is a semiconductor device based on transfer of hot electrons between separately contacted conducting layers. The nature of hot‐electron injection by the real‐space transfer allows the implementation of novel circuit elements. In particular, we propose a multiterminal single‐device structure that works as a functional element with three logic inputs Xj (j=1,2,3) and one output equal to (X1∩X2∩X3)∪(X1∩X2∩X3). This device, called the norand, can perform both as a nor(X1,X2) and as an and(X1,X2) element, reprogrammable electrically by changing the X3 input. The operation of norand with logic gain is demonstrated experimentally by an equivalent circuit connection of discrete charge injection transistors implemented within InGaAs/InAlAs on InP technology.

High transconductance and large peak‐to‐valley ratio of negative differential conductance in three‐terminal InGaAs/InAlAs real‐space transfer devices

Three‐terminal real‐space transfer devices with improved room‐temperature characteristics have been implemented in InGaAs/InAlAs/InGaAs heterostructures lattice matched to InP. The devices exhibit extremely sharp charge injection, characterized by a transconductance exceeding 23 S/mm and a negative differential conductance with a peak‐to‐peak ratio of over 7000. Our experiments suggest that both of these characteristics are limited only by the dielectric strength of the InAlAs barrier layer.

Spatial resolution of the capacitance‐voltage profiling technique on semiconductors with quantum confinement

The spatial resolution of the capacitance‐voltage profiling technique on semiconductors with one‐dimensional quantum confinement is shown to be given by the spatial extent of the wave function. The Debye length limitation does not apply. Capacitance‐voltage profiles on δ‐doped GaAs of density 4–4.5×1012 cm−2 exhibit widths of 20 and 48 A for p‐ and n‐type impurities, respectively. The profiles agree with the theoretical resolution function and with Be and Si profiles measured by secondary‐ion mass spectroscopy. It is further shown that the saturation of the free‐carrier density of highly Si δ‐doped GaAs grown by molecular beam epitaxy is due to inactive Si impurities

Ultrahigh speed modulation‐doped heterostructure field‐effect photodetectors

We have developed a sensitive, ultrahigh speed photodetector which has a structure of a modulation‐doped AlxGa1−xAs/GaAs field‐effect transistor. In spite of a large gate‐drain spacing of >8 μm and a gate length of >20 μm, this detector exhibited a rise time of 12 ps and a full width at half‐maximum of 27 ps. When tested by a 8200‐A GaAs injection laser, the detector showed an ac (>20 MHz) external quantum efficiency of >630%, i.e., 9 times more sensitive than a pin photodiode. In view of its high sensitivity, ultrahigh speed, and compatibility with modulation‐doped field‐effect transistors, this detector has promise for a variety of high‐speed optical applications.

Ga0.47In0.53As ultrahigh gain, high sensitivity photoconductors grown by chloride vapor‐phase epitaxy

We report highly sensitive planar, interdigitated Ga0.47In0.54As photoconductive detectors prepared by trichloride vapor‐phase epitaxy. The devices exhibit dc gains as high as 104 at 1.3 μm. For a bit rate of 500 Mbit/s a sensitivity of P=−35.4 dBm has been measured at 1.55 μm. With devices having unity gain quantum efficiencies of η=33% we obtain ηP=−40 dBm matching the highest sensitivity measured with a p‐i‐n photodetector at similar bit rates. The devices show responsivities in excess of 3000 A/W and detectivities ranging between 1012 and 1013 cm Hz1/2 W−1. These values represent the highest performance that has ever been achieved with photoconductors in this wavelength range.

Depletion mode modulation doped Al 0.48 In 0.52 As-Ga 0.47 In 0.53 As heterojunction field effect transistors

We report the first demonstration of a depletion mode modulation doped Ga0.47In0.53As field effect transistor. This transistor combines the advantage of modulation doping and the superior material characteristics of Ga0.47In0.53As. DC transconductances of 31 mmho/ mm at 300 K and 69 mmho/mm at 77 K have been measured for a device with 5.2µm gate length and 340 µm gate width. An enhanced drift mobility is responsible for 88 percent of the improvement in the transconductance at 77 K and the remaining 12 percent is attributed to an improved ohmic contact. A high performance modulation doped Ga0.47In0.53As FET is expected to play an important role in very high speed digital and analog applications.

Direct measurement of the carrier leakage out of the active region in InGaAsP/InP laser heterostructures

Leakage of electrons out of the active region of InGaAsP/InP laser heterostructures at different temperatures was measured by a purely electrical method. Comparison of the obtained results with the results of modeling indicates that special attention should be paid to the acceptor doping levels in the p cladding layer immediately adjacent the active region. Lower acceptor concentration may lead to unacceptably high thermionic leakage. >

Electro‐optic sampling measurements of high‐speed InP integrated circuits

Multigigahertz waveforms in an InGaAs/InP metal‐insulator‐semiconductor field‐effect transistor inverter circuit have been measured noninvasively using the electro‐optic sampling technique with pulses from a gain‐switched InGaAsP laser. Propagation delays as low as 15 ps in a single inverter stage have been measured.

Monolithically integrated InGaAs/InP MSM-FET photoreceiver prepared by chemical beam epitaxy

The first monolithic integration of a metal-semiconductor-metal (MSM) InGaAs photodetector with a field-effect transistor (FET) and resistors into a high-impedance front-end photoreceiver circuit is discussed. The sample was grown in a single step by chemical beam epitaxy, and standard processing steps for making FETs were used to fabricate the receiver circuit. Semi-insulating Fe-doped InP layers were used as the insulating gate of the FET, the barrier enhancement layer in the MSM photodetector, and the electrical isolation layer between the photodetector and the electronic circuit. A bit error rate of less than 10/sup -9/ at 200 Mb/s has been achieved with this preliminary circuit for an optical power of -17 dBm. >