Single-drift IMPATT Research Articles

Low noise, high efficiency GaAs IMPATT diodes at 30 GHz

Low noise, very high efficiency IMPATT diodes provide an attractive alternative to Gunn diodes for many millimetre-wave applications. In the Letter, GaAs Hi–Lo single-drift IMPATT diodes are demonstrated. The diodes are fabricated using molecular beam epitaxy and (at ~30 GHz) exhibit exceptional efficiencies (>20%), very low FM noise (–88 dBc/Hz at 100 kHz off-carrier) and simultaneous CW power levels in excess of 300 mW.

A Computer Study on the High Frequency Properties of Silicon mm-Wave Single Drift Impatt Diodes

A detailed investigation on dc and high frequency properties of silicon single drift Impatt devices is presented for device operation at the frequencies of 35, 94, 140 and 220 GHz which are the atmospheric window frequencies for mm—wave signals. A comparative account of device properties of n+ pp+ and p+ nn+ SDRs is also presented. Single drift Impatts at frequencies beyond 100 GHz are characterised by very high electric fields at the metallurgical Junction, wide avalanche zone and low breakdown and drift voltages. The magnitude of field maximum for Si n+ pp+ SDR increases from a value of 38.5 V/μm to 93.7 V/μm when the frequency of operation increases from 10 GHz to 140 GHz. The ratio VD/VA for n+ pp+ diode which is nearly unity for X-band operation drops down to only 0.16 for operation at frequencies around 150 GHz. The computed values of normalized avalanche zone width of Si n+ pp+ diodes are found to be only 30%, 60% and 70% respectively for operation at 10 GHz, 94 GHz and 140 GHz as against the corre...

Low-noise D-band IMPATT oscillators

The single-sideband FM noise characteristics of IMPATT diode oscillators for D-band frequencies have been measured by means of a direct-detection system with a high-Q quasi-optical resonator. For an n-type silicon single-drift IMPATT diode a Δfrms of 11 Hz/√Hz and a noise measure of 37 dB at 137.5 GHz and 26 mW output power was determined.

High-power pulsed beam-lead IMPATT diodes for millimetre waves

IMPATT diodes with technologically integrated beam-leads were fabricated. Since no diode bonding is required, a total diode thickness of less than 2 μm can be realised reproducibly. With optimum device packages, peak pulse output powers of more than 10 W at 70 GHz have been achieved from silicon single-drift IMPATT diodes.

High-efficiency single-drift GaAs IMPATT diodes for 72 GHz

High-efficiency GaAs single-drift IMPATT diodes have been developed up to 72 GHz using molecular-beam epitaxy. The design of the devices is based on a lower value of the electron drift velocity at high electric fields. The diodes are bonded on diamond heat sinks. The best efficiencies are 12.5% at 63 GHz with 450 mW output power and 10% at 72 GHz with 350 mW output power.

Single drift impatt diodes on diamond heat sinks for W-band frequencies

High-power silicon pnn+ impatt dioes have been fabricated by a simple diffusion process for operation on diamond heat sinks. The maximum outputpower of 0.5 W has been achieved at 90 GHz with diodes of 46 fim in diameter. Owingto the low thermal resistance of 11 K/W the corresponding junction temperature is considerably below 200°C.

Millimeter-Wave Silicon IMPATT Sources and Combiners for the 110-260-GHz Range

This paper reports recent progress in CVV and pulsed silicon IMPATT sources in the 110-260-GHz frequency range. Pulsed output power levels of 3, 1.3, and 0.7 W, and CW output power levels of 110, 60, and 25 mW have been consistently achieved from single-drift IMPATT diodes at 140, 170, and 217 GHz, respectively. A Read-type IMPATT diode that generated good output power over a wide frequency range was fabricated. A bridged double-quartz standoff package was developed and successfully used for the entire frequency range. Power combiners at center frequencies of 140 and 217 GHz were developed with peak output power of 9.2 and 1 W, respectively.

Efficient p-type Si IMPATT diodes for V-band frequencies

p-type single-drift IMPATT diodes for V-band frequencies were fabricated by a single diffusion process. The diodes were packaged on a copper heatsink using quartz standoffs and investigated in a resonant cap waveguide structure. The maximum CW output power is 0.5 at 68 GHz with an efficiency of 8.7%

Pulsed V-band m.b.e. Si IMPATT diodes

Single drift Impatt diodes of m.b.e. material are described which deliver pulse output power over 5 W at V-band. Maximum chirp frequency is less than 10 MHz, making the devices favourable for coherent radar applications.

Ion-implanted p–n junction indium-phosphide impatt diodes

Implantation of beryllium ions into a uniformly doped n-type InP epitaxial layer grown by vapour-phase epitaxy has been utilised to create a p+?n junction for flat-profile single-drift impatt diodes. An r.f. performance comparable to gallium arsenide has been obtained. A c.w. output power of 1.6 W with 11.1% conversion efficiency has been measured at 9.78 GHz and a peak power of 6.1 W with 13.7% efficiency has been measured at 10.8 GHz with 10% duty cycle. The f.m. noise of the c.w. oscillators is comparable to results reported for silicon.

Shifting of the peak generation rate in double-drift silicon IMPATT diodes

In double-drift (DD) silicon IMPATT diodes, it is observed that the peak generation rates of both carriers (electrons and holes) lie within the n side. The shifting is due to the unequal ionization rates for electrons and holes in silicon. By neglecting the reverse saturation current, a simple analytical expression for the location where the peak generation occurs is derived. This simple result may be useful for the design of double-drift as well as complementary single-drift IMPATT diodes.