gated diode
**Gated diode** is a **test structure for junction characterization** — combining a PN junction with a gate electrode to enable comprehensive characterization of junction properties, leakage mechanisms, and interface quality in semiconductor devices.
**What Is Gated Diode?**
- **Definition**: PN junction with gate electrode for enhanced characterization.
- **Structure**: PN diode with MOS gate over junction region.
- **Advantage**: Gate control enables detailed junction analysis.
**Why Gated Diode?**
- **Junction Characterization**: Measure junction depth, doping, leakage.
- **Leakage Mechanisms**: Identify bulk vs. surface leakage.
- **Gate Control**: Modulate surface to isolate leakage sources.
- **Process Monitor**: Track junction formation quality.
- **Reliability**: Assess junction breakdown and degradation.
**Measurements**
**I-V Characteristics**: Forward and reverse junction current.
**Leakage Current**: Reverse bias leakage at various gate voltages.
**Breakdown Voltage**: Maximum reverse voltage before breakdown.
**Ideality Factor**: Junction quality from forward I-V.
**Gate-Controlled Leakage**: Surface vs. bulk leakage separation.
**Gate Voltage Effects**
**Accumulation**: Gate attracts majority carriers to surface.
**Depletion**: Gate depletes surface of carriers.
**Inversion**: Gate inverts surface, creating channel.
**Leakage Modulation**: Gate voltage changes surface leakage.
**Applications**: Junction leakage monitoring, process development, reliability testing, failure analysis, surface passivation evaluation.
**Advantages**: Separates surface and bulk leakage, comprehensive junction characterization, gate control for detailed analysis.
**Tools**: Semiconductor parameter analyzers, probe stations, automated test equipment.
Gated diode is **powerful for junction analysis** — by adding gate control to a simple diode, it enables detailed characterization of junction properties and leakage mechanisms critical for device performance and reliability.