For electronic applications, a series of boron-doped homoepitaxial diamond layers of high crystal quality have been grown on (100)-cut diamond substrates using the microwave plasma CVD method. The B-concentration varies from 3 x 1017 to 3 x lozo atoms/cm3. The layers are selectively grown into the shape of Hall bars using a sputtered SiOn mask. The diamond substrates are 3 x 3 x 1 mm3 in size. Gold wires are bonded to ohmic contacts on the Hall bars formed by an electron beam evaporated Mo/Pt/Au sandwich annealed at 950 "C for 30 min. Electrical characterization is performed in eight samples over the temperature range from 100 to 1300 K. The results arc discussed in detail. For diamond layers grown on synthetic nitrogen-doped (type Ib) substrates, current-voltage characteristics of diode type can be observed in the temperature range from 360 to 900 "C. Green electroluminescent light is emitted from the p-n junction area. High current Schottky diodes are also fabricated which consist of a gold contact to a moderately B-doped homoepitaxial layer grown on a synthetic heavily boron-doped (type I1 b) substrate. Fur elektronische Anwendungen wird eine Serie von Bor-dotierten homoepitaktischen Diamantschichten hoher kristalliner Gute auf (100)-geschnittenen Diamantsubstraten mittels der Mikrowellenplasma-unterstutzten CVD-Methode aufgewachsen. Die B-Konzentration variiert von 3 x 1017 bis 3 x lozo Atome/cm3. Die Schichten werden selektiv mittels gesputterter SiOz-Masken als Hallkreuze gewachsen. Die Diamantsubstrate sind 3 x 3 x 1 mm3 grof3. Golddrahtc werden an ohmsche Kontakte gebondet. Diese werden als Mo/Pt/Au-Schichtpakete mittels Elektronenstrahl-Aufdampfen und halbstundigem Tempern bei 950 "C hergestellt. Die elektrische Charakterisierung erfolgt bei acht Proben iiber den Temperaturbereich von 100 bis 1300 K. Die Ergebnisse werden eingehend diskutiert. Auf synthetischen Stickstoff-dotierten (Typ I b) Substraten werden Strom/ Spannungs-Charakteristikcn vom Diodentyp im Temperaturbereich von 360 bis 900 "C beobachtet. Grunes Elektrolumineszenzlicht wird von der p-n-Kontaktflache emittiert. Hochstrom-Schottkydioden werden ebenfalls hergestellt. Sie bestehen aus einem Goldkontakt zu einer m a i g B-dotierten homoepitaktischen Schicht, die auf einem synthetischen, hochdotierten (Typ I1 b) Substrat aufgewachsen wurde.T. H. BOWT and 0. WEIS EB = 0.37 eV, if moderately doped, and becomes metallic with EB = 0 eV for heavy d o p ing. Thus, suitably B-doped diamond can be used over a broad temperature range for p-type conduction. Substitutional single nitrogen atoms are donors [2] with an ionization energy EB = 1.7 eV which is too high for a utilizable n-type conduction at room temperature. At present, there is no n-type diamond available for applications at room temperature. Nevertheless, due to the exceptional physical properties of diamond [3], a variety of unusual electronic applications of semiconducting diamond are expected [4 to 61.Electronic diamond devices of high quality can only be demonstrated in monocrystalline...

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Abstruct-Epitaxial p-type Schottky diodes have been fabricated on p+-substrate. While the activation energy of the epitaxial layer conductivity is 390 meV, that of the substrate is only 50 meV. At forward bias the substrate conductivity dominates above 150 "c, leading for a 5 x cm2 area contact to a series resistance of 14 R at 150 "C reducing to 8 R at 500 "C. To our knowledge, this is the lowest series resistance reported so far for a diamond Schottky diode enabling extremely high current densities of lo3 Alcm and a current rectification ratio at =t2 V of lo5 making these diodes already attractive as high temperature rectifiers.