A Schottky barrier diode swaps the p-n junction's two doped semiconductor regions for a single metal-semiconductor interface, and that one substitution changes almost everything about how the device behaves: forward voltage drops lower, switching happens faster, and the entire conduction mechanism shifts from a junction that stores and must remove minority carriers to one that never stores them in the first place. The metal chosen to form that junction is not incidental, it is the single parameter that sets the barrier height, and barrier height is the number that governs almost every electrical trade-off the device makes. That single-parameter leverage is what makes the Schottky diode such a flexible building block: a designer facing a new power-conversion, clamping, or RF-detection requirement can often meet it simply by picking a different contact metal rather than redesigning the entire junction structure from scratch.

Barrier height, denoted Phi-B, forms at the metal-semiconductor interface as a direct consequence of the metal's work function relative to the semiconductor's electron affinity, and it is this single energy parameter that sets how easily carriers can cross the junction in either direction. On n-type silicon, common Schottky metals produce barrier heights spanning roughly 0.5 eV to 0.9 eV, with titanium sitting toward the lower end of that range and platinum or molybdenum sitting higher, giving a designer real latitude to trade forward drop against reverse leakage simply by choosing a different contact metal. Because barrier height is set at the interface itself rather than by bulk doping the way a p-n junction's built-in potential is, a Schottky diode's electrical behavior is unusually sensitive to interface cleanliness, and any interfacial oxide or contamination layer measured in a fraction of a nm can measurably shift the effective barrier seen by carriers. Barrier height uniformity across a wafer is commonly held within a few % of target, since a wider spread produces a correspondingly wide spread in forward voltage across devices meant to be electrically matched. Interfacial cleanliness is typically qualified to keep native-oxide-equivalent thickness under about 0.5 nm before metal deposition, since a thicker interfacial layer inserts an unwanted series element that distorts the ideal thermionic-emission I-V relationship the device is designed around.

Low forward voltage drop is the Schottky diode's signature advantage over a conventional p-n diode, and it follows directly from the lower effective barrier a majority carrier has to cross compared with the built-in potential of a doped p-n junction. A representative silicon Schottky diode turns on around 0.2 V to 0.4 V, well below the roughly 0.6 V to 0.7 V turn-on typical of a silicon p-n diode, and that difference of several hundred mV translates directly into lower conduction loss in any application where the diode carries current continuously. In a power-conversion circuit switching at high frequency, that forward-drop advantage compounds across millions of switching cycles per second, making the difference between a Schottky rectifier and a p-n rectifier a meaningful contributor to overall system efficiency rather than a minor detail. Because forward drop depends directly on barrier height, a lower-Phi-B metal choice can push VF down further still, though always at the cost of higher reverse leakage, which is the central trade-off metal selection has to balance.

Majority-carrier operation is the structural reason a Schottky diode switches so much faster than a p-n diode: with no minority-carrier injection into the metal, there is no stored minority charge that has to be swept out or recombined before the diode can turn off. A p-n diode's reverse-recovery time, the delay caused by clearing stored minority carriers, can run into the tens of ns depending on the diode's doping and geometry, while a comparable Schottky diode's reverse recovery is dominated almost entirely by junction capacitance charging and typically completes in well under 1 ns. This speed advantage is why Schottky diodes dominate RF detection and high-frequency rectification applications where a p-n diode's reverse-recovery delay would otherwise limit the usable switching frequency to well below what the circuit actually needs. Switching waveforms are commonly characterized at frequencies from a few MHz up to several hundred MHz to confirm that reverse recovery stays negligible across the diode's intended operating range.

Reverse leakage current is the price paid for a Schottky diode's low forward drop, and the trade-off runs in a predictable direction: the lower the barrier height chosen to minimize VF, the higher the thermionic-emission-driven leakage current under reverse bias. A high-Phi-B metal choice like platinum can hold reverse leakage to a small fraction of what a low-Phi-B metal like titanium would produce at the same reverse voltage, but that leakage reduction comes paired with a higher forward voltage drop, so metal selection is never optimized for one parameter alone. Reverse leakage also rises steeply with temperature, since thermionic emission over the barrier is thermally activated, and a Schottky diode qualified at room temperature can show reverse leakage several times higher at an elevated junction temperature of 125 °C. Reverse breakdown voltage for a Schottky rectifier is generally lower than for a comparably sized p-n diode, which is one more reason Schottky devices are typically used at moderate voltage ratings rather than pushed into high-voltage blocking applications.

Silicide Schottky contacts, using NiSi, PtSi, or similar reacted metal-silicon compounds, have become the practical standard for on-chip Schottky diodes because the silicide reaction produces a reproducible, well-characterized barrier height that a simple deposited metal film cannot match as consistently. Because the silicide forms through a controlled thermal reaction rather than being merely deposited, its interface with the underlying silicon is cleaner and more uniform, directly improving barrier-height reproducibility from device to device and wafer to wafer. NiSi Schottky contacts in particular are attractive because the same silicide module already used for transistor source-drain contacts can double as the Schottky diode's metal-semiconductor junction, avoiding an entirely separate process module. Contact resistance and barrier height for a silicide Schottky diode are typically qualified together, since a process drift that shifts one almost always shifts the other in a correlated way. Silicide reaction temperature for a NiSi Schottky module commonly runs near 400 °C to 500 °C, the same low-temperature phase window used for source-drain silicide, letting the diode's contact form during a step the flow already performs elsewhere.

On-resistance and current-handling capability round out the practical device parameters that determine where a Schottky diode fits in a real circuit, and both depend on the same barrier-height and doping choices already discussed. Series resistance in the drift region beneath the Schottky junction is minimized by tuning doping concentration and drift-region thickness, a balance that also sets the diode's reverse blocking voltage, so on-resistance and voltage rating cannot be optimized independently, and drift-region resistivity is routinely checked with a four-point probe alongside a SIMS dopant depth profile to confirm the doping gradient matches the design target before the diode is committed to a full electrical characterization run. A power Schottky rectifier commonly targets an on-resistance low enough to keep conduction loss under a few % of total delivered power at rated current, a specification that depends on both barrier height and drift-region design landing within their qualified windows simultaneously. Forward current rating for a typical discrete Schottky rectifier can range from under 1 A for a small-signal RF detector diode up to several tens of A for a power-conversion rectifier, with drift-region thickness and area scaled accordingly to hold the rated on-resistance at that current level. Temperature behavior of on-resistance is also tracked, since resistance in the lightly doped drift region typically rises measurably as junction temperature climbs from room temperature toward 125 °C or higher under sustained load.

Select Schottky contact metal for target barrier height → Form metal-semiconductor junction, PVD or silicide reaction → Verify Phi-B and interface quality → Characterize forward I-V and reverse leakage → Measure reverse recovery and switching speed → Qualify on-resistance and temperature behavior → Release for rectifier or RF detection application

Viewed through a Schottky barrier-height engineering lens, the entire diode reduces to a single design decision, which metal to react with which semiconductor, propagating through forward drop, reverse leakage, switching speed, and temperature behavior all at once, so that the finished rectifier lands exactly where a power-conversion, clamping, or RF detection application actually needs it on that shared trade-off curve.