IV.25 - GaAs PIN Power Diodes?

A now-defunct company called International Semiconductor (ISSM) and its subsiduary, GAD Semiconductor, developed power GaAs PIN diodes. These are not Schottky diodes. This information was extracted from ISSM's 10-K form, filed with the the Securities and Exchange Commission (who would've thought of the SEC database as a good place to research diodes?!) :

• The vast majority of semiconductor devices are made of silicon, whose physical properties limit high temperature and high frequency operations at elevated temperatures. Although gallium arsenide semiconductor devices offer significantly better operating parameters, past attempts to form an actual high-voltage gallium arsenide positive-intrinsic- negative ("P-i-N") structure, which would have properties superior to a silicon structure, have failed due to complications in technology, irreproducibility of results and defects that led to low breakdown voltages. GAD acquired, from the Ramot University Authority for Applied Research and Industrial Development, Ltd., of Tel Aviv, a royalty-free exclusive license to exploit certain technology relating to a method of forming a gallium arsenide PiN structure for use in diodes and thyristors. Patents have been filed under the Patent Cooperation Treaty, which will allow protection in up to 56 countries which belong to the world patent treaty.

  GAD succeeded, during 1995, in producing a diode which operates at high temperatures, is stable and highly efficient. This diode does not therefore require cooling, thereby reducing the cost of the packaged product significantly, and making it price- competitive with silicon. GAD's product keeps its electrical charge throughout the entire temperature spectrum. The processing speed of silicon is also reduced at high voltage and high power whereas GaAs can combine high voltage and high speed. During late 1995, GAD developed a new series of diodes with record fast switching times approaching 14 nanoseconds. This product was designed especially for Power Factor Correction Applications, a market segment which is expected to grow very fast in the next few years. In April, 1996, GAD is introducing a high-current, 20 ampere diode, as an addition to currently produced 10 ampere diodes. Several new devices will be introduced in the remainder of 1996. GAD's range of diodes will be sold as components to a large number of industries. These include automotive, aerospace, radar and communications, X-Ray equipment, defense (command and control systems), night vision and other areas where an uninterrupted power supply is required.

  Existing Product

  GAD's gallium arsenide-based power switching diodes offer the following significant advantages over available silicon-based diodes:

  Higher operating temperature (260 C vs. 150 C for
  silicon diodes)
  High breakdown voltage (as high or higher than 
  silicon diodes)
  Ultra-fast switching frequency (comparable to silicon
  diodes at room
  temperature, and at
  higher frequency at
  elevated temperatures)
  Temperature independent (temperature dependent in
  silicon diodes)
  switching frequency 
  Lower reverse leakage (2 orders of magnitude lower
  than silicon diodes)
  current at both room
  and high operating temperature
  Low capacitance and low dependance
  on reverse bias
  High forward current
  Forward current "derating" (starts at 100 C for
  silicon diodes) 
  starts at 160 C 
  

  GAD's products now offer users the following principal benefits:

  Combination of high voltage, high forward current and very small switching time (a combination which is basically unavailable in silicon diodes);

  Reliable operation at high temperatures;

  Smaller cooling systems required (typically 5 times smaller in volume and weight than for silicon diodes); and

  Higher efficiency/smaller power losses than in silicon diodes at high frequencies (because of lower leakage current, lower capacitance and lower dependency of maximum voltage, current and switching frequency on temperature).

  Manufacturing

  During 1994, the company completed construction and run-in of its state-of-the-art manufacturing facility in Migdal Haemek (near Nazareth), in Ramot Gabriel, the largest high-tech industrial park in Israel. The plant, occupying 8,000 square feet, is capable of producing between 8,000,000 to 10,000,000 diodes per year, and can be expanded in a relatively short period with the addition of more processing equipment. Throughout 1995, GAD produced several runs of its diodes for distribution to potential customers, delivered the diodes for testing, and has been receiving commercial orders from several of the testing sources. See Marketing, Sales and Distribution below.

  GAD does not perform the packaging assembly of the diodes, but has this done by sub-contractors in Israel and abroad, and by actual customers, depending on contracting and marketing agreements it reaches with foreign vendors of diodes and rectifier power diodes.

  Marketing, Sales and Distribution

  The Company believes that the electrical characteristics of GAD's gallium arsenide based PiN diode for high frequency rectification and power conversion systems, including very fast switching at high voltage and currents, stable recovery times, low leakage current, ultra-low capacitance and very high peak operating temperature, provide a "performance envelope" of combined characteristics superior to silicon-based diodes. The parameters of GAD's gallium arsenide power diodes allow the engineering community to make more cost- effective and more reliable circuitry designs, providing superior solutions to the ones previously available through silicon semiconductor diodes. These diodes should have market applications in power supplies, welding machines, motor drives, radar and fiber optic communications. For example, since the operating temperature for GAD gallium arsenide diodes is superior to silicon (260 C v. 150 C), engineers can design cooling systems (heat sinks) which, for a typical high power application, will be much smaller in volume and in weight.

  GAD's diodes will not compete in the highly volatile semiconductor integrated circuit business, but rather in the specialty, discrete electronic components markets. GAD entered a one early-phase contract for packaging and distribution with OMNIREL CORP., an American company supplying diodes to the U.S. military. A large American semiconductor company is in its final stages of testing (over 1 year already invested) GAD's products in anticipation of a long-term, high volume contract with GAD. A team from a different customer is currently investigating the Migdal Ha'mek facilities to confirm the company's capability of delivering sizable volumes with sustained quality control, also incipient to a long-term, medium volume contract, and two Japanese customers are well along in their time-vs-performance testing of the products.

  Research and Development

  The Company believes that the technical specifications of the gallium arsenide P-i-N diode structure make it suitable for additional applications beyond power rectifier diodes. Some of the future product lines which GAD hopes to develop include switching transistors, TGBT, thermosensors, x-ray detectors, neutron detectors, ultra-low capacitance capacitors, and novel controlled semiconductor capacitors (varactors).